Atari* System Reference manual (c) 1987 By Bob DuHamel Bob Duhamel 6915 Casselberry Way San Diego, CA 92119 *Atari is a registered trademark of Atari Corp. This manual contains highly technical information. Such information is provided for those who know how to use it. To understand the advanced information you are expected to know 6502 assembly language. If you are new to programming, concentrate on the parts which discuss BASIC commands. Addresses are usually given in both hexadecimal and decimal numbers. The operating system equate names are given in capital letters with the address following in brackets. The decimal address is in parenthsis within the brackets. For example: DOSVEC [$000A,2 (10)] name hex dec The ",2" after the hexadecimal number means that this address requires two bytes to hold its' information. Any address called a "vector" uses two bytes whether noted or not. Control registers and some other bytes of memory are shown in the following format Register format 7 6 5 4 3 2 1 0 ----------------- | | ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 The numbers on top are the bit numbers. Bit 7 is the Most Significant Bit (MSB) and bit 0 is the Least Significant bit (LSB). The numbers on the bottom are the bit weights. These are useful when changing memory with decimal numbers, as you would in BASIC. For example, to set bit 4 of a register to 1, without changing any other bits you would add 16 to the decimal number already in the register. To reset the same bit to 0, you would subtract 16 from the number in the register. This is exactly what the command GRAPHICS 8+16 does. It sets bits 3 and 4 of a graphics mode control register. MSB and LSB may also mean Most Significant Byte or Least Significant Byte, depending on context. CONTENTS 1 THE CENTRAL INPUT/OUTPUT UTILITY, (CIO) 2 THE DISK OPERATING SYSTEM (D:) 3 USING THE DOS 2 UTILITIES (DUP.SYS) 4 THE CASSETTE HANDLER (C:) 5 THE KEYBOARD HANDLER (K:) 6 PRINTER HANDLER (P:) 7 SCREEN EDITOR (E:) 8 THE DISPLAY HANDLER (S:) 9 THE RESIDENT DISK HANDLER 10 SYSTEM INTERRUPTS 11 THE FLOATING POINT ARITHMETIC PACKAGE 12 BOOT SOFTWARE FORMATS 13 THE SERIAL INPUT/OUTPUT INTERFACE (SIO) 14 THE HARDWARE CHIPS 15 DISPLAY LISTS 16 PLAYER AND MISSILE (PM) GRAPHICS 17 SOUND 18 THE JOYSTICK PORTS 19 MISC 20 THE XL AND XE MODELS CHAPTER 1 THE CENTRAL INPUT/OUTPUT UTILITY, (CIO) The ATARI computer uses a very easy-to-use input and output system called the Central Input/Output utility, or CIO. Nearly all input or output passes through this utility. CIO uses eight "channels" as paths for I/O. There are not really separate channels for I/O but the computer acts as if there were. Each channel is controlled by a 16 byte block of memory called an Input/Output Control Block or IOCB. The channels are used by putting the proper numbers in the proper IOCB bytes then jumping to the CIO routine. In BASIC, complete I/O operations can be as easy as typing a command such as LPRINT. In this case BASIC does all the work for you. THE CIO CHANNELS There are eight CIO channels, numbered from 0 to 7. In BASIC some channels are reserved for BASIC's use. BASIC CIO channel assignments Channel 0 Permanently assigned to the screen editor 6 Used for graphics commands 7 Used for the Cassette, disk and printer Channels 6 and 7 are free to use when they are not being used by BASIC. With machine language, all of the channels are available to the programmer. THE IOCB STRUCTURE The IOCB for channel zero starts at address $0340 (decimal 832). This is the only address you need to know. Indexing from this address is used to find all of the other bytes. Below are the names and uses of the IOCB bytes. IOCB bytes and uses: ADDRESS NAME EXPLANATION $0340 ICHID handler Identifier $0341 ICDNO device number (disk) $0342 ICCOM command $0343 ICSTA status $0344 ICBAL buffer address (low byte) $0345 ICBAH buffer address (high byte) $0346 ICPTL address of put byte $0347 ICPTH routine (used by BASIC) $0348 ICBLL buffer length (low byte) $0349 ICBLH buffer length (high byte) $034A ICAX1 auxiliary information $034B ICAX2 - $034C ICAX3 the remaining auxiliary $034D ICAX4 bytes are rarely used $034E ICAX5 - $034F ICAX6 - ICHID When a channel is open, the handler I.D. contains an index to the handler table. The handler table (to be discussed later) holds the address of the device handling routines. When the channel is closed ICHID contains $FF. ICDNO The device number is used to distinguish between multiple devices with the same name, such as disk drives. ICCOM The command byte tells CIO what operation to perform. CIO command codes HEX DEC +Open $03 3 +close $0C 12 get $07 7 put $09 11 input $05 5 print $09 9 +status request $0D 13 +*special >$0D >13 + command may be made to a closed channel * device specific commands ICSTA The status byte contains an error code if something goes wrong. If bit 7 is 0 there have been no errors. ICBAL and ICBAH Before a channel is opened, the buffer address bytes are set point to the block of memory which contains the name of the device the channel is to be opened to. Before actual input or output these bytes are set to point to the block of memory where the I/O data is stored or is to be stored. ICPTL and ICPTH The put routine pointer is set by CIO to point to the handlers' put-byte routine. When the channel is closed the pointer points to the IOCB-closed routine. This pointer is only used by BASIC. ICBLL and ICBLH The buffer length bytes show the number of bytes in the block of memory used to store the input or output data. (See ICBAL and ICBAH.) If the amount of data read during an input operation is less than the length of the buffer, the number of bytes actually read will be put in ICBLL and ICBLH by CIO. ICAX1 through ICAX6 The auxiliary information bytes are used to give CIO or the device any special information needed. OPENNING A CIO CHANNEL Before using a CIO channel it must be assigned to an I/O device. In machine language you start by putting the channel number in the four high bits of the 6502 X register (X = $30 for channel three). Next you place the necessary codes (parameters) into IOCB 0 indexed by X. The X register will cause the numbers to be offset in memory by 16 times the channel number. This puts the numbers into the correct IOCB instead of IOCB 0. Below are the parameters used to open a channel. Channel-open parameters: ICCOM open code ICBAL address of device name ICBAH in memory ICAX1 direction code ICAX2 zero The direction code byte in ICAX1 takes on the following format: ICAX1 format for opening a channel 7 6 5 4 3 2 1 0 ----------------- ICAX1 | W R | ----------------- 8 4 2 1 W 1 = open for output (write) R 1 = open for input (read) ICAX1 may have the following data CIO direction codes HEX DEC operation $04 4 input $08 8 output $0C 12 input and output (cannot change the length of a disk file) ICBAL and ICBAH point to the device name stored in memory. The device and file name must be followed by 0 or $9B (decimal 155). Once the parameters are set, jumping (JSR) to the CIO vector (CIOV) at address $E456 (58454) will cause the channel to be opened. In the following example a basic knowledge of assembly language is assumed. Routine to open channel 1 to the keyboard: ICHID = $0340 ICCOM = ICHID+2 ICAX1 = ICHID+10 ICAX2 = ICHID+11 IOCB1 = $10 channel in four high bits CIOV = $E456 OPEN = $03 OREAD = $04 ;open for input ERROR = (address of error handling routine) ; START LDX IOCB1 LDA OPEN STA ICCOM,X LDA NAME STA ICBAH,X LDA OREAD STA ICAX1,X LDA #0 STA ICAX2,X JSR CIOV BPL OK JMP ERROR ; NAME .BYTE "K:",$9B OK (program continues here) To open a CIO channel in BASIC the OPEN command is used. BASIC OPEN command format: OPEN #channel,aux1,aux2,device:file name aux1 = direction code aux2 = special code To open channel 1 to the keyboard in BASIC Type: OPEN #1,4,0,"K:" The third parameter, aux2, is a rarely used special parameter. One use is to keep the screen from erasing when changing graphics modes. The fourth parameter is the device to open the channel to. It may be either a string in quotes or a string variable. CIO device names C cassette recorder *D disk drive E screen editor K Keyboard P printer *R RS 232 I/O port S screen handler * Uses a non-resident handler loaded by the device at power-up. The device name must usually be followed by a colon. With the disk drive a file name is expected after the device name. The screen handler is used for graphics. The screen editor uses both the keyboard handler and the screen handler to work between the keyboard and screen. USING AN OPEN CHANNEL Once a channel is opened to a device you have several options: INPUT: (ICCOM = $05) The computer reads data from the device until a carriage-return is read (decimal number 155, hex $9B) or the end of the file (EOF) is reached. A carriage return is also known as an End-Of-Line or EOL. The IOCB input parameters are: IOCB input parameters: ICCOM get record code ICBAL address of buffer to ICBAH store the data in ICBLL length of the data ICALH buffer The following routine demonstrates the input command in assembly language. Some of the equates are in the channel openning example above. Input routine: GETREC = $05 BUFF = (address to store data at) BUFLEN = (number of bytes available at storage address) : LDX IOCB1 LDA GETREC STA ICCOM,X LDA < BUFF STA ICBAL,X LDA > BUFF STA ICBAH,X LDA < BUFLEN STA ICBLL,X LDA > BUFLEN STA ICBLH,X JSR CIOV BPL OK2 JMP ERROR : OK2 (continues if no errors) If the data retrieved is shorter than the prepared buffer, the number of bytes actually read will be put into ICBLL and ICBLH. In BASIC, the INPUT command is used. BASIC INPUT command format: INPUT #channel,string variable or INPUT #channel,arithmetic variable For example: INPUT #1,IN$ The above commands will cause the data from the device to be put into the specified buffer (IN$ in the BASIC example) until an EOL is reached. If the INPUT statement is used again, without closing the channel, the computer will get more data from the device until another EOL is read or the end of the file is reached. The new data will write over the old data in the input string or buffer. If an arithmetic variable is used, only numbers can be input. PRINT: (ICCOM = $09) In assembly language the print command is identical to the input command. The only difference is that the PUTREC code ($09) is stored in ICCOM. Of course the buffer bytes of the IOCB then specify the block of memory to be output from rather than input to. With the print command, EOLs within the string or buffer are ignored but an EOL is placed at the end of the data when sent to the device. In BASIC, the PRINT command is used like INPUT except you want to use a semicolon instead of a comma to separate parameters. For example: PRINT #1;OUT$ or PRINT #1;"HELLO" If you use a comma, ten space characters will be sent before the string. If the print command is used again, without closing the channel, the new data will be appended to the end of the data previously sent. Old data will not be written over. GET: (ICCOM = $07) In BASIC this command inputs a single byte of data from the device. EOLs are ignored. In BASIC, GET is used like INPUT except an arithmetic variable must be used. For example: GET #1,IN If the get command is used again the next byte from the device will be read. If the end of a file is reached an error will occur. There is no command in BASIC to input an entire file without stopping at each EOL. If you wish to ignore EOLs while reading a file to a string, you must use the GET command. Each byte of data is then put into the string by the program. EXAMPLE: 10 OPEN #1,4,0,"D:TEST" 20 TRAP 60:REM GOES TO LINE 60 WHEN END OF FILE ERROR OCCURS 30 GET #1,IN 40 IN$(LEN(IN$)+1)=CHR$(IN) 50 GOTO 30 60 CLOSE #1 In assembly language, the get command can be used to get any number of bytes from the device. It works just as INPUT does except EOLs are ignored. IOCB get-byte parameters: ICCOM get-character (single byte) code ICBAL \ ICBAH same as in input ICBLL ICBAH / Other than the ICCOM code (GETCHR = $07) this command is identical to the input command. PUT: (ICCOM = $0B) In BASIC, PUT is the opposite of GET. It outputs a single byte from a variable to the device. PUT is used the same as GET. For example: PUT #1,OUT In assembly language, the command byte of the IOCB is loaded with the put-character code (PUTCHR = $0B). Otherwise the PUT command is identical to GET. CLOSING A CHANNEL Closing a channel frees it for use by another device or for changing parameters. In assembly language the close code is put into the command byte of the IOCB then the CIOV call is made. IOCB close command: CLOSE = $0C : LDX IOCB1 LDA CLOSE STA ICCOM,X JSR CIOV In BASIC, use the CLOSE command followed by the channel number. CLOSE #1 With the disk drive, the file name is not put into the directory until the channel is closed. THE DEVICE TABLE CIO uses a jump table located at $031A (794). When a CIO call is made, CIO searches the table for the one-byte device name. The two bytes following the device name contain the address of the device handler's vector table. CIO searches the device table from the end, $033D (829) to the beginning. This way, if a custom handler has ben substituted for a resident handler, the custom handler will be found first. (custom handlers cannot be inserted directly in the place of resident handlers in the device table.) Each handler has its' own vector table. This vector table is 16 bytes long. The two-byte vectors point to the various handler routines. The vectors are stored in the vector table in the following order: Handler vector table order open close get byte put byte get stat special JMP init code (3 bytes) The open routine should validate the ICAX parameters and check for illegal commands. The close routine should send any remaining data in the buffer to the device, mark the End-Of-File and update any directories, etc. The get byte routine should get a byte from the device or the handler buffer and put it in the 6502 A register. Handlers with long timouts must monitor the break key flag and put a $80 in the 6502 Y register if the [BREAK] key is pressed. The put byte routine should send the byte in the 6502 A register to the device or handler buffer. If the buffer fills, it should be sent to the device. BASIC can call the put byte routine without using CIO. The get status routine may get 4 bytes of status information from the device and put them in DVSTAT [$02EA] to DVSTAT+3. For special commands the handler must examine the command byte and find the proper routine entry point. In all cases the status (error code) of the operation should be put in the 6502 Y register. To be compatible with all versions of the operating system, the handler must redirect DOSINI [$000C,2 (12)] for initialization upon reset. This initialization must restore the vectors in the handler vector table and jump to the origional DOSINI vector. SPECIAL COMMANDS Some devices have special CIO commands. These are known as device specific commands. In assembly language these commands are executed just as any other CIO command is. In BASIC the XIO command is used. An example of the XIO command is: XIO command code #channel,aux1,aux2,device:file name To open a channel with the XIO command instead of the OPEN command use: XIO 3 #1,4,0,"K:" Note that the above command is identical to the OPEN command except "XIO 3" is used instead of "OPEN". Also note that $03 is the IOCB open code for ICCOM. Useful database variables and OS equates DOSINI $000C,2 (12): initialization vector BRKKEY $0011 (17): break key flag ICHID $0340 (832): start of IOCBs ICDNO $0341 (833): ICCOM $0342 (834): ICSTA $0343 (835): ICBAL $0344 (836): ICBAH $0345 (837): ICPTL $0346 (838): ICPTH $0347 (839): ICBLL $0348 (840): ICBLH $0349 (841): ICAX1 $034A (842): ICAX2 $034B (843): HATABS $031A,16 (794): device handler table CIOV $E456 (58454): CIO entry vector CHAPTER 2 THE DISK OPERATING SYSTEM (D:) The disk operating system program (DOS) is also called the file management system (FMS). DOS is not a permanent part of the computer, it is loaded in upon power-up if a disk drive is attached to the computer. When the computer is turned on, one of the first things it does is send a request to the disk drive to load DOS into the computer. This startup operation is called booting. The word boot is short for bootstrapping -- the start-up process of early computers. The term comes from "lifting one's self by one's boot straps". Anytime the disk boots, the computer tries to read a program starting at sector 1 and continuing in sequence. If the disk has DOS on it, the first three sectors, called the boot record, have a program which loads the DOS.SYS file. If there is no DOS.SYS file on the disk the computer will display: -------------------- | BOOT ERROR | | BOOT ERROR | | BOOT ERROR | | BOOT ERROR | | BOOT ERROR | | BOOT ERROR | | (etc.) | | | | | -------------------- When a disk is formatted, the drive read/write head passes over the entire disk and puts magnetic marks on it. These marks divide the disk into 32 concentric tracks. With DOS 2.0 each track is divided into 18 sectors, each holding 128 bytes of data. With DOS 2.5 there are 32 sectors per track giving a total of 1,024 sectors. Each sector on the disk is marked with a reference number from 1 to 720. Unfortunately, the writers of DOS 2.0 didn't know this so they wrote the DOS to use sectors numbered from 0 to 719. As a result, DOS 2.0 cannot access sector 720. The designers of the disk drive were the guilty party in this case. It is normal to number from 0 in computers. With DOS 2.5, sectors 720 - 1,024 can be accessed normally. Sector 720 can be accessed using the computer's resident disk handler. Some software writers use sector 720 to hide special information to make their programs difficult to copy. DOS 2 SECTOR ASSIGNMENTS Sectors 1 through 3 are called the boot record. They contain a program which loads the DOS.SYS file into memory. Sector 360 is called the Volume Table of Contents or VTOC. The main purpose of the VTOC is to keep track of what sectors are occupied. Bytes 3 and 4 of the VTOC tell how many sectors are available. Starting at byte 10 is the Volume Bit Map. Each byte in the VBM tells the status of eight sectors. If a bit is a 1 the sector is available. If a bit is a 0 the sector is occupied. Sectors 361 through 368 contain the disk directory. Each directory sector holds eight file names. The first byte of a file name is called the flag byte. It tells the status of that file. Directory flag byte. 7 6 5 4 3 2 1 0 ----------------- | flag byte | ----------------- Bits: 7 1 = file deleted 6 1 = file in use 5 1 = file locked 0 1 = open for output The next two bytes tell how many sectors are in the file. The two bytes after them tell the starting sector of the file. The last 11 bytes contain the file name. Sector 720 cannot be accessed with DOS 2.0. The boot record, VTOC, directory and sector 720 use 13 sectors. This leaves 707 sectors for storing files with DOS 2.0. Each file sector has 125 bytes of data. The last three bytes tell how many bytes of the sector are used, what directory entry the sector belongs to and which sector is next in the file. File sector structure 7 6 5 4 3 2 1 0 ----------------- | data | byte 0 - - - - | bytes | byte 124 ----------------- | Dir. No. |hi | byte 125 ----------------- |forward pointer| byte 126 ----------------- |S| byte count | byte 127 ----------------- hi = high 2 bits of forward pointer S = Short sector flag. 1 = short sector (End Of File) If the directory number does not match the order of the file name in the directory, an error 167 (file number mismatch) will occur. As a file is written to an empty disk it is put in consecutive sectors, 125 bytes at a time. After the file is written, the VTOC and directory are updated. When new files are written they also use consecutive sectors. When a file is deleted the status bit of the directory is changed to show that the file has been deleted. DOS then tracks the file, sector by sector, to find what sectors are used. Finally the VTOC is updated to show that the deleted file's sectors are available for new files. The file is not erased from the disk; only the VTOC and directory are changed. When a file is deleted, an "island" of free sectors may be left on the disk. When a new file is then written to the disk it will first use these new free sectors. When the island is used up, DOS will skip over the occupied sectors to the next free sector. This is the reason for the sector link. A file can end up with it's sectors scattered all over a disk. It can be complicated but it's efficient. DISK FILE STRUCTURE The first few bytes of a file may tell DOS or another program what kind of file it is. These information bytes are called a header. A text file is any file which has no header. A listed BASIC program is a type of text file. A letter from a word processor is another. A binary load file is a file intended to load to a specific address in memory. The first two bytes of a binary load file are decimal 255. The next two bytes hold the address at which the file is to load. The last two header bytes tell the ending address for the file. If the file is a program and is to run automatically, the initialization and run address are appended to the end of the file. binary load file header Decimal Hexadecimal 255 identifier FF 255 FF 0 start 00 7 07 15 end FF 8 08 The above file would load at address $0700 (1792 decimal) and end at address $08FF (2063). If a binary load file has initialization and run address appended to it they take on the following format: Init and run tailer CHR Decimal Hexadecimal init address format [b] 226 identifier E2 | 2 02 [c] 227 E3 | 2 02 n address nn n nn run address format [diamond] 224 identifier E0 | 2 02 [a] 225 E1 | 2 02 n address nn n nn [ ]=inverse video A program which doesn't need special initialization can be run at the init address. Otherwise, an RTS instruction is expected at the end of the initialization section. The computer will then jump to the run address if specified. INSIDE THE COMPUTER DOS uses the computer's CIO utility. When a DOS disk is booted a non-resident handler is loaded into memory. A new handler name, D, is then added to the handler table. When CIO is called with a device name of D: or Dn:, CIO will search the handler table for that device name. If the 'D' is found, the next two bytes in the table point to the DOS entry address. DOS FILE NAME CONVENTIONS DOS is unique among CIO handlers in that it requires an eight character file name to follow the device name. This file name may be followed by a period and then a three character extender. EXAMPLES: D:TEST, D2:FIREMAN, D:VENTURE.EXE, D:CHAPTER.001 The D2: is used for drive number two if present. The file name must use upper-case letters or numbers. The first character must always be a letter. WILD CARDS The characters * and ? may be used as wild cards. * means any combination of characters and ? means any single character. EXAMPLES: D:P* any file beginning with P and without an extender D:*.EXE any file with the extender .EXE D:*.* any file. D:F?REMAN one unknown character, FIREMAN or FOREMAN will match Wild cards can only be used to load, delete, lock and unlock files. When loading a file using wild cards, only the first matching file will be loaded. When renaming a file, both the new and old names are expected after the device name. EXAMPLE: D:OLDNAME.BAS,NEWNAME.BAS To format a disk, only the device name (D: or Dn:) is needed. USING DOS When a CIO channel is opened to the disk drive it must actually be opened to a specific file on the disk. The device name in the open command must be followed by a file name. When a channel is opened to the disk, two special parameters may be used in ICAX1. ICAX1 for disk open: 7 6 5 4 3 2 1 0 ----------------- | W R D A| ----------------- D 1 = open to read the directory instead of a file A 1 = append data to the end of the file This gives the following extra ICAX1 options. Disk specific ICAX1 options: HEX DEC $06 6 open to read directory $09 9 output, append to the end of an existing file READING THE DIRECTORY When the directory is read, each file name is treated as if it were followed by an EOL. A loop must be used to read all of the file names in the directory. The last entry read is the free sector count. After it is read, another read operation will result in an End-Of-File error. The disk drive has a number of device specific commands other than the regular CIO commands. From BASIC the XIO command is used to access these commands. The XIO command allows you to directly load the IOCBs from BASIC. Each parameter of the XIO command places values in certain bytes of an IOCB. XIO command format: XIO command channel,aux1,aux2,device:file name Note that the parameters resemble the BASIC OPEN command. The BASIC OPEN command is identical to it's equivalent XIO command. XIO commands specific to the disk drive. RENAME XIO $20 (32) DELETE XIO $21 (33) LOCK XIO $23 (35) UNLOCK XIO $24 (36) POINT XIO $25 (37) NOTE XIO $26 (38) FORMAT XIO $FE (254) EXAMPLES: XIO 33 #1,0,0,"D:JUNK" = delete file named D:JUNK XIO 32 #1,0,0,"D:OLD,NEW" = change name of D:OLD to D:NEW NOTE and POINT can also be used directly from BASIC. NOTE finds the current position of the read/write head on the disk. POINT moves the read/write head to the desired position. USING NOTE AND POINT The command format for NOTE and POINT is as follows: NOTE \ channel,sector,byte POINT/ EXAMPLE: NOTE #1,SECT,BYTE BASIC requires the sector and byte parameters in both commands to be variables. Fixed numbers cannot be used. If you try to do a POINT to a sector outside the file the channel is open to, a point error will occur. Care may need to be taken to be sure the file being accessed is in contiguous sectors on the disk. If it is not, it will be difficult to know where to do points to. One use of NOTE is to use the command immediately after opening a channel to a disk file. After the NOTE command, the parameter variables contain the coordinates of the first byte of the file. They can then be used as a reference for the POINT command. In assembly language, ICAX3 and ICAX4 are used for the sector number (lsb,msb). ICAX5 is used for the byte number. STATUS REQUEST If the status request command is used, one of the following values will be found in ICSTA and the 6502 Y register. HEX DEC $01 1 OK $A7 167 file locked $AA 170 file not found CHAPTER 3 USING THE DOS 2 UTILITIES (DUP.SYS) If you boot a DOS disk with no cartridge in the slot or with BASIC disabled (by holding the OPTION key), DOS will try to load the file named DUP.SYS. This is the disk utility file. When using BASIC, typing DOS [RETURN] will load the DUP.SYS file. When the utilities are loaded the menu will appear on the screen. THE DOS UTILITIES MENU DISK OPERATING SYSTEM II VERSION 2.0S COPYRIGHT 1980 ATARI A. DISK DIRECTORY I. FORMAT DISK B. RUN CARTRIDGE J. DUPLICATE DISK C. COPY FILE K. BINARY SAVE D. DELETE FILE(S) L. BINARY LOAD E. RENAME FILE M. RUN AT ADDRESS F. LOCK FILE N. CREATE MEM.SAV G. UNLOCK FILE O. DUPLICATE DISK H. WRITE DOS FILES SELECT ITEM OR [RETURN] FOR MENU [A] DIRECTORY After pressing [A] [RETURN] you will get the prompt: DIRECTORY--SEARCH SPEC,LIST FILE? If you want to see the entire directory just press [RETURN] again. If you wish, you may type in a specific file name (D: is optional) or wild cards to search for. If you specify a search spec only matching files will be displayed. If you want, you can have the directory sent to another device. To do this type a comma and the device name. For example, if you type ,P: the directory will be sent to the printer. [B] RUN CARTRIDGE If a cartridge was inserted or BASIC was not disabled when the computer was turned on, [B] [RETURN] will run that cartridge or BASIC. [C] COPY FILE This option will copy a file to another part of the same disk (with a different file name) or copy from one disk drive to another. When you press [C] [RETURN] you will be given the prompt: COPY--FROM,TO Type the devices and file names separated by a comma. EXAMPLES: FOREMAN,FIREMAN or D1:TEST,D2:TEST The first example will copy to the same disk. The second example will copy from disk drive one to disk drive two. If you want to have the first file appended to the end of the second file type /A after the file names. EXAMPLE: RUNMENU.EXE,AUTORUN.SYS/A If the files are binary load files, this will cause both files to be saved as one file. When the load command is used they will both be loaded and run. [D] DELETE FILE(S) After pressing [D] [RETURN] you will get the prompt: DELETE FILE SPEC After typing the file name you will be asked to confirm the file to delete. DELETE FILE SPEC DELETE-D1:JUNK ARE YOU SURE? Press [Y] if the correct file is displayed. If you use wild cards you will be asked to confirm each matching file. [E] RENAME Upon typing [E] [RETURN] you will be given the prompt: RENAME-GIVE OLD NAME,NEW Type the file name you want to change and the new name separated by a comma. EXAMPLE: COLT,HORSE WARNING! Do not rename a file to a name which already exists on the disk. You will end up with a duplicate file name and will not be able to access one of them. Attempting to rename or delete one of them will rename or delete both. The only way to fix a duplicate file name is with a sector editor or other special utility. [F] LOCK FILE A locked file cannot be written to, renamed or deleted. To lock a file type [F] [RETURN]. You will get the prompt: WHAT FILE TO LOCK? Type the file name you want to lock. Wild cards will cause all matching files to be locked. [G] UNLOCK FILE Used the same as lock. [H] WRITE DOS FILES This option will write the DOS.SYS and DUP.SYS files to a formatted disk. When you type [H] [RETURN] you will receive the prompt: DRIVE TO WRITE DOS FILES TO? Type the number of the drive. If the drive contains a formatted disk the dos files will be written to it. [I] FORMAT DISK This option formats a new disk or erases a disk with files on it. Typing [I] [RETURN] will get you the prompt: WHICH DRIVE TO FORMAT Be sure you have the correct disk in the proper drive then type the drive number. It is impossible to recover files on a disk formatted by accident. While the disk is being formatted the drive will check to be sure the disk is formatted correctly. If not, the drive attempt to format the disk again. If the disk is defective the drive will not finish the formatting process. [J] DUPLICATE DISK This option will copy an entire disk except for sectors listed as free in the VTOC. Some programs are copy-proofed by changing the VTOC to show that some occupied sectors are empty. For such disks, a program which copies the entire disk is needed. When you press [J] [RETURN] you will be given the prompt: DUP DISK--SOURCE,DEST DRIVES? If you are using only one disk drive, type 1,1. If you have only one drive you will be told when to swap disks. [K] BINARY SAVE This option saves a block of memory as a binary load file. When you type [K] [RETURN] you will be given the prompt: SAVE-GIVE FILE,START,END(,INIT,RUN) Type the desired file name and a comma. Now type the start and end addresses of the memory block to be saved, in hexadecimal numbers, separated by commas. If the file is a program which is to automatically run when loaded, give the initialization address, if needed, then the run address. EXAMPLE: CHASE.EXE,0700,09FF,,0700 This will save the block of memory from address 0700 to 09FF. The program is not initialized before running so there is no address typed after the third comma. When the program is loaded the computer will jump to address 0700, as specified in the last parameter, to run the program. [L] BINARY LOAD To load a binary file type [L] [RETURN]. You will get the Prompt: LOAD FROM WHAT FILE? Type the file name and the file will be loaded. If wild cards are used, only the first matching file will be loaded. [M] RUN AT ADDRESS Typing [M] [RETURN] will get the prompt: RUN FROM WHAT ADDRESS? Type the hexadecimal address of the program you want to run. [N] CREATE MEM.SAV A MEM.SAV file is used by BASIC and some other programs to save the part of memory which the DUP.SYS file loads into. If there is no MEM.SAV file on the disk when you go to the DOS utilities, you will loose that part of memory. With BASIC you will loose your program. When you type [N] [RETURN] you will get the prompt: TYPE Y TO CREATE MEM.SAV Typing [Y] [RETURN] will create a MEM.SAV file on the disk in drive one. [O] DUPLICATE FILE This option is used to copy a file from one disk to another, using only one disk drive. When you type [O] [RETURN] you will get the prompt: NAME OF FILE TO MOVE? If you use wild cards you will be asked to swap disks for each matching file. DOS 2.5 also has option: [P] FORMAT SINGLE DOS 2.5 normally formats disks to use "enhanced" density. This option will format a disk in single density for use with the 810 drive. DOS 2.5 also has some special utilities on the master disk. Use the binary load option to run them. RAMDISK.SYS This program will cause the extra bank of memory in the 130XE to act like a disk drive (called D8:). If this program is on the disk it will automatically run. It need not be renamed to AUTORUN.SYS. COPY32.COM Copies DOS 3 files to DOS 2. DISKFIX.COM Can make certain "repairs" to a disk, such as restoring deleted files. SETUP.COM Used to change the default configuration of DOS. AUTORUN.SYS (DOS 2.0 and 2.5) This program is needed to operate the RS-232 ports on the 850 interface. If you don't want this program to automatically load when you boot with the master disk, rename the file to RS232. SPECIAL DOS INFORMATION When DOS is in memory, changes can be made to the DOS program. These changes can be made by poking the changes into memory. If you want to make the changes permanent, you can type DOS [RETURN] to load the utilities. From the utilities menu you can use the write DOS files option to save the changes on disk. Some of the useful changes you can make follow. POKE 1913,80 This turns off the write verify and speeds up disk writing. POKE 1913,87 This turns write verify on POKE 5903,42 POKE 5904,46 POKE 5905,82 POKE 5906,85 POKE 5907,78 POKE 5908,155 This causes any binary file with the extender .RUN to be loaded automatically when the computer is turned on. POKE 5903,65 POKE 5904,85 POKE 5905,84 POKE 5906,79 POKE 5907,82 POKE 5908,85 This returns the DOS to normal, Automatically loading files named AUTORUN.SYS. DOS 2.0 DOS 2.5 POKE 3772,255 POKE 3818,64 POKE 3774,64 POKE 3822,123 POKE 3778,123 This will cause DOS to accept lower-case as well as upper-case letters in file names. It will also now accept @,[,\,],^ and _ . POKE 3772,223 POKE 3818,65 POKE 3774,65 POKE 3822,91 POKE 3778,91 This will change DOS back to normal, accepting only upper-case letters and numbers. CHAPTER 4 THE CASSETTE HANDLER (C:) The cassette handler sends data to the cassette recorder in blocks of 128 bytes each. The blocks are sent in the following format: Cassette record format ----------------- |0 1 0 1 0 1 0 1| speed measurement bytes ----------------- |0 1 0 1 0 1 0 1| ----------------- | control byte | ----------------- | 128 | = data = | bytes | ----------------- | checksum | handled by SIO ----------------- The control byte may have one of the following values. $FC (252) record is full. $FA (250) partly full, next record is EOF. $FE (254) EOF record, data section is all zeroes. The cassette handler has two modes of operation. The first mode uses only a short gap between records. It is called the no IRG (interrecord gaps) mode. The second mode uses longer gaps between records and is called the IRG mode. In the IRG mode the computer may stop the cassette recorder between records for processing data. When a channel is opened to the cassette recorder, bit 7 of ICAUX2 may be set to 1 (ICAX2 = $80 (128)). This will cause the cassette to use the no IRG mode. A cassette file starts with a 20 second mark tone. This tone is followed by the file records with 128 data bytes each. The final record is an End-Of-File record. The cassette is a straight-forward read/write device. There are no special functions other than those common to other CIO devices. The cassette motor is controlled by one of the controller port control registers. If bit 3 of PACTL [$D302 (54018)] is 0 then the cassette motor is on. The following BASIC commands will turn the cassette motor on and off. Cassette motor control. POKE 54018,PEEK(54018)-8 motor on POKE 54018,PEEK(54018)+8 motor off Useful data base variables and OS equates PACTL $D302 (54018): port A control register, bit 4 controls cassette motor CHAPTER 5 THE KEYBOARD HANDLER (K:) The keyboard is a read only device and therefore the keyboard handler has no output functions. The keyboard handler reads the keys as ATASCII codes. Each key is represented by one byte of data. Therefore, each time a key is pressed the data is treated as a byte of data just as data from any other device is. The only difference is that the computer must wait for the operator to press the keys as it reads the data. Whenever a key is pressed an IRQ interrupt is generated by the keyboard reading hardware. The internal code (not ATASCII) for the key just pressed is then stored in CH [$02FC (764)]. The code is then compared with the prior key code in CH1 [$02F2 (754)]. If the code in CH1 is different from the code in CH, the key is accepted. The code is then converted to ATASCII, and placed in the database variable ATACHR [$02FB (763)]. On XL and XE models, KEYDEF [$0079,2 (121)] points to the key-code-to-ATASCII conversion table. (This address is used by the the screen handler in 400/800 models). If the code in CH1 is the same as the code in CH, the new key code will not be accepted unless the key debounce timer, KEYDEL [$02F1 (753)] is 0. When CIO is told to do an input operation from the keyboard, CH is checked to see if a key has been pressed. If CIO finds $FF (255) in CH, it waits until a key is pressed. If CH is not $FF, a key has been pressed and the ATASCII code for that key is taken from ATACHR. CH is then set to $FF. The data in CH is in the following format. Key code format: 7 6 5 4 3 2 1 0 ----------------- |C|S| key code | ----------------- C 1 = [CTRL] key is pressed S 1 = [SHIFT] key is pressed Anytime a key is pressed, CH is loaded with the key code. CH will hold the code until the computer is commanded to read the keyboard. Sometimes the computer will read a key which was pressed long ago. If you want to prevent this, load CH with $FF before reading the keyboard. (In BASIC use POKE 764,255.) This will clear out any old key pressings. Special function keys [CTRL][1] screen output start/stop [CTRL][2] BELL [CTRL][3] Generates End-Of-File status [/|\] or [/] inverse video toggle [CAPS LOWER] sets lower case [CTRL][CAPS] sets CTRL lock [SHIFT][CAPS] sets caps lock KEYBOARD REPEAT DELAY AND RATE CONTROL On the XL and XE, KRPDEL [$02D9 (729)] determines the delay before the key repeat begins. The value of this byte is the number of vertical blanks (1/60th second each) to delay. KEYREP [$02DA (730)] determines the repeat rate in vertical blanks. KEYBOARD CLICK The keyboard click of the XL/XE is heard through the TV speaker. The click may be turned off by putting $FF in NOCLIK [$02DB (731)]. NON-HANDLER, NON-CIO KEYS The [OPTION], [SELECT] and [START] keys are read from the console switch register, CONSOL [$D01F (53279)]. The console switch register 7 6 5 4 3 2 1 0 ------------------------- CONSOL |0 |0 |0 |0 |SP|OP|SE|ST| ------------------------- 8 4 2 1 ST 0 = [START] SE 0 = [SELECT] OP 0 = [OPTION] SP Console speaker. set to 1 during vertical blank. toggleing this bit operates the speaker (which is heard through the TV on XL/XE models). This bit always reads 0 The [HELP] key on XL and XE models is read from HELPFG, [$02DC (732)]. This address is latched and must be reset to zero after being read. The [HELP] key register 7 6 5 4 3 2 1 0 ----------------- HELPFG |C S 0 H 0 0 0 H| ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 H 1 = [HELP] (bits 0 and 4) S 1 = [SHIFT] C 1 = [CONTROL] Useful database variables and OS equates KEYDEF $0079,2 (121): key code coversion table vector (XL/XE) KRPDEL $02D9 (729): delay before key repeat (XL/XE) KEYREP $02DA (730): key repeat rate (XL/XE) NOCLIK $02DB (731): $FF turns off key click (XL/XE) HELPFG $02DC (732): [HELP] key (XL/XE) ATACHR $02FB (763): ATASCII Code for last key CH $02FC (764): keycode, $FF if no key has been pressed BRKKEY $0011 (17): break key flag, 0 = break key pressed SRTIMR $022B (555): Key delay and repeat timer SHFLOK $02BE (702): SHIFT/CTRL lock flag $00 = lower case $40 (64) = upper case lock $80 (128) = CTRL lock INVFLG $02B6 (694): inverse video flag, non-zero = inverse CONSOL $D01F (53279): start, select and option keys IRQEN $D20E (53774): IRQ interrupt enable bit 7 enables [BREAK] bit 6 enables other keys shadow registers POKMSK $0010 (16): IRQEN shadow CHAPTER 6 THE PRINTER HANDLER (P:) The printer is a write only device so the printer handler has no input functions. The printer handler has no special functions other than the CIO functions common to all other devices. Although many printers have special functions, the printer handler has no control over them. See your printer manual for information on special functions. CHAPTER 7 SCREEN EDITOR (E:) The screen editor uses both the keyboard handler and the screen handler to provide interactive control of the computer. In fact, the keyboard handler, the screen handler and the screen editor are contained in a single section of code and are therefore very closely related. The editor works with one line of characters at a time. The lines it works with are called logical lines and are up to three screen lines long. The screen editor inputs data from the keyboard and then prints the data on the screen. When the [RETURN] key is pressed, the editor inputs all of the data on the present logical line for processing by CIO. If characters are typed on the screen, and then the cursor is moved off the line, then back on the line, and new characters are typed, only the characters to the right of the reentry point of the cursor are input when [RETURN] is pressed. However, if the cursor is moved off the line again, then moved back on, all characters on that logical line are input. If bit 0 of ICAX1 is 1, the editor will act as if the [RETURN] key is being held down. This bit may be changed at any time. Editor control codes The screen editor treats certain ATASCII codes as special control codes. Screen editor control codes KEY HEX DEC FUNCTION [RETURN] $9B 155 carriage return or EOL [CLEAR] $7D 125 Clear screen,put cursor in upper left [UP ARROW] $1C 28 Move cursor up one screen line [DOWN] $1D 29 down one line [LEFT] $1E 30 left one character [RIGHT] $1F 31 right one character [BACK S] $7E 126 Back-space operation [SET TAB] $9F 159 sets tab stop at cursor [CLEAR TAB] $9E 158 Clear tab stop at cursor [TAB] $7F 127 move to next tab stop [SHIFT] [INSERT] $9D 157 Make space for a new line [SHIFT] [DELETE] $9C 156 delete the logical line at the cursor [CTRL] [INSERT] $FF 255 make room for a character [CTRL] [DELETE] $FE 254 delete character at cursor [ESCAPE] $1B 27 causes next non-EOL code to be displayed as an ATASCII character, even if it is an editor control code [CTRL][1] screen print start/stop [CTRL] $FD CHAPTER 8 THE DISPLAY HANDLER (S:) The display handler manages the computer's video display. Although no data ever leaves the computer through it, the display is treated like any other CIO device. Data sent to the screen may be displayed as either characters or point by point graphics. Although it is only visible in the 40 column text mode, mode 0, there is a cursor on the screen in all of the text or graphics modes. Whenever a character or graphics point is put on the screen, the cursor moves just as in mode 0. The display is capable of both input and output. Information can be put on the screen with any of the CIO output commands. An input command will find whatever is on the screen at the position of the cursor. When text or graphics is sent to the screen it is actually stored in an area of memory called the display buffer. What you see on the screen is the computer's interpretation of the data stored there. This will be explained further as each mode is covered. DISPLAY HANDLER SPECIAL FUNCTIONS: DRAW FILL SPECIAL ERROR STATUSES: $84 (132) Invalid special command. $8D (141) Cursor out of range. $91 (145) Nonexistant screen mode. $93 (147) Insufficient ram for screen mode. TEXT MODE 0 In graphics mode 0, data passes through CIO, and is stored in the display buffer in the following format. 7 6 5 4 3 2 1 0 ----------------- |I| Data | ----------------- I 1 = displays character in inverse video. Bits 0 through 6 select one of the 128 characters in the ATASCII set. If bit seven = 1, the character is displayed in inverse video. Converting the above byte to decimal will give the BASIC ASC(x) equivalent. The characters displayed in the text modes are determined by tHE ATASCII character set. This is a bit by bit representation of how the characters appear on the screen. The character set starts $E000 (57344) in the operating system ROM. From there, for 1K of memory, each eight bytes holds a "bit map" of a particular character. Below is how the letter A is stored in the character set. Letter A as represented in the C-set 7 6 5 4 3 2 1 0 ----------------- $E208 |0 0 0 0 0 0 0 0| ----------------- |0 0 0 1 1 0 0 0| * * ----------------- |0 0 1 1 1 1 0 0| * * * * ----------------- |0 1 1 0 0 1 1 0| * * * * ----------------- |0 1 1 0 0 1 1 0| * * * * ----------------- |0 1 1 1 1 1 1 0| * * * * * * ----------------- |0 1 1 0 0 1 1 0| * * * * ----------------- $E20F |0 0 0 0 0 0 0 0| ----------------- XL and XE models have an international character set starting at $CC00 (55224). In this character set the graphics characters are replaced by international characters. Custom characters sets may be loaded at any free address which is a multiple of 1,024 ($0400, or 1K). The database variable CHBAS [$02F4 (756)] stores the most significant byte (MSB) of the address of the active C-set. Since the LSB of the C-set address is always $00, no LSB is needed to find it. The data stored in the display buffer does not use the ATASCII code. A special code needed by the ANTIC chip is used. DISPLAY CODE / ATASCII CODE CONVERSION: ATASCII display $00 - $1F ( 0 - 31) = $40 - $5F (64 - 95) $20 - $5F (32 - 95) = $00 - $3F ( 0 - 63) $60 - $7F (96 - 127) = unchanged The codes for inverse video (the above codes with bit 7 set (= 1) or the above codes + 128 in decimal) are treated likewise. When you first turn on the computer, BASIC opens channel 0 to the screen editor (E:). The screen editor uses both the keyboard handler and the screen handler, in mode 0, to display characters when they are typed in. TEXT MODES 1 AND 2 Graphics modes 1 and 2 offer a split screen configuration if desired. The split screen has four lines of mode 0 at the bottom of the screen. In mode 1 the screen holds 20 characters horizontally and 24 characters vertically. In mode 2 the characters are twice as tall so the screen holds 12 vertically. In BASIC, characters are sent to the screen with the PRINT command. Since BASIC uses channel 6 for graphics you must specify channel 6 in the command. For example: ? #6;"HELLO" If you use a comma in place of the semicolon, ten spaces will print before the "HELLO" You can also use the PLOT and DRAWTO commands. In this case the COLOR command determines the character, as well as the color to be displayed. Data passes through CIO in the following form: 7 6 5 4 3 2 1 0 ----------------- | C | D | ----------------- C determines the color. C Default Color Shadow Color Register Register 0 green COLPF1 COLOR1 1 gold COLPF0 COLOR0 2 gold COLPF0 COLOR0 3 green COLPF1 COLOR1 4 red COLPF3 COLOR3 5 blue COLPF2 COLOR2 6 blue COLPF2 COLOR2 7 red COLPF3 COLOR3 D is a 5 bit ATASCII code which selects the character to be displayed. The database variable CHBAS selects between upper case (CHBAS=$E0 (224)) and lower case (CHBAS=$E2 (226)). GRAPHICS MODES 3 THROUGH 11 Modes 3 through 8 offer a split screen mode. In modes 9 through 11 special programming is required for split screens. These modes use dot by dot (pixel by pixel) graphics instead of character sets. Before explaining how graphics are sent to the screen through CIO, I will describe how the data in the display buffer is interpreted by the ANTIC chip. Mode 8 is the simplest of the graphics modes. Each byte of the display buffer controls eight pixels horizontally. The first 40 bytes of the display buffer control the first horizontal line of graphics. This makes a total of 320 pixels horizontally. If one of the eight bits of a byte is a 1 then the pixel it controls is on. If a bit is a 0 then it's pixel is off. For example, if a particular byte is equal to $9B (binary 10011011) then its' part of the screen would look like... * ** ** (10011011) In reality the pixels are assigned to different color registers. A color register is a byte of memory which controls the color of all pixels assigned to it. In mode 8, if a bit is = 0 it's pixel is assigned to the register called COLBK. If a bit is one, it's pixel is assigned to COLPF0. See COLORS below for more information on the color registers. You may notice a close similarity between mode 0 and mode 8. The major difference between these modes is where the dot by dot information comes from. In mode 8 this information comes from the display buffer. In mode 0 the display buffer contains codes telling what characters to display. The actual dot by dot information comes for the character set at $E000. In mode 7 each pixel is controlled by two bits. Therefore each byte only controls four pixels. There are also only 1/4 as many pixels on the screen as in mode 8. See mode 3 below for an explanation of how the each byte affects the pixels. In a graphics mode, when CIO sends a byte of data to the screen handler, that byte has information for only one pixel. Do not confuse a byte which CIO sends to the screen handler with the bytes in the display buffer. CIO sends data to or retrieves data from the screen in the following forms. 7 6 5 4 3 2 1 0 ----------------- |0 0 0 0 0 0| D | Modes 3,5,7 -- D = color ----------------- ----------------- |0 0 0 0 0 0 0|D| Modes 4,6,8 -- D = Color ----------------- ----------------- |0 0 0 0| D | Modes 9,10,11 -- D = data ----------------- Mode 3 uses a screen which is 40 pixels horizontally and 24 vertically. Each pixel is a square the size of a mode 0 character. It requires 273 bytes of RAM where each byte controls 4 pixels. Each pair of bits controls which of the four color registers their pixel is assigned to. display buffer byte for mode 3 7 6 5 4 3 2 1 0 ----------------- | D | D | D | D | ----------------- P1 P2 P3 P4 Pixel/color register assignments: D = 00 COLBK (COLOR4) 01 COLPF0 (COLOR0) 10 COLPF1 (COLOR1) 11 COLPF2 (COLOR2) Mode 4 uses a screen of 80 columns by 48 rows. Each pixel is half the size of those in mode 3. Mode 4 requires 537 bytes of RAM where each byte controls 8 pixels. This mode is very similar to mode 8 except there are fewer but larger pixels. Mode 5 uses a screen of 80 columns by 48 rows. The pixels are the same size as in mode 4. Mode 5 requires 1,017 bytes of RAM where each byte controls 4 pixels in the same manner as in mode 3. Mode 6 uses a screen of 160 columns by 96 rows. It requires 2,025 bytes of RAM where each byte controls 8 pixels as in mode 4. Mode 7 uses a screen of 160 columns by 96 rows. It requires 3,945 bytes of RAM where each byte controls 4 pixels as in modes 3 and 5. Modes 8 through 11 (and 15 on XL and XE models) each require 7,900 bytes of RAM and are very similar in display set up. The main differences between these modes is the interpretation of data in the display buffer. Mode 15 (sometimes called mode 7.5) uses a screen of 160 columns by 192 rows. Each byte controls 4 pixels as in mode 7. The main difference between mode 15 and its related modes is bit 0 of each instruction byte in the display list (the program which the ANTIC chip uses). If this bit is 0 the screen is interpreted as mode 15. If the bit is 1 the screen is interpreted as modes 8 through 11. Modes 8 through 11 are set up identically in memory, including the display list. The only difference is the data in the PRIOR register of the GTIA chip. The shadow register for PRIOR is GPRIOR [$026F (623)]. Mode 8 (PRIOR = $00 - $3F (0 - 63)), uses a screen of 320 columns by 192 rows. Each byte controls 8 pixels as in modes 4 and 6. Mode 9 (PRIOR = $40 - $7F (64 - 127)) uses a screen of 80 columns by 192 rows. Each byte controls 2 pixels. The pixels are all of the same color, controlled by COLBK. Each half of a byte in the display buffer controls the luminance of the assigned pixel. The format of each byte is as follows. 7 6 5 4 3 2 1 0 ----------------- | data | data | ----------------- pixel 1|pixel 2 Mode 10 (PRIOR = $80 - $BF (128 - 191), is the same as mode 9 except 9 color luminance combinations are available. The data in each half byte chooses one of the 9 color registers for the assigned pixel. Mode 11 (PRIOR = $C0 - FF (192 - 255), is the same as mode 9 except there is one brightness but 16 colors. The pixel data chooses one of the 16 available colors. The luminance is that of the background (COLBK). USING THE SCREEN HANDLER OPENING A CHANNEL TO THE SCREEN HANDLER When a channel is opened to the screen handler the following actions take place: The area of memory to be used for the screen data is cleared. A display list (program for the ANTIC chip) is set up for the proper graphics mode. The top-of-free-memory pointer, MEMTOP [$02E5,2 (741)], is set to point to the last free byte before the display list. Before opening a channel to the screen handler, the pointer to the highest memory address needed by the program, APPMHI [$000E,2 (14)], should be properly set. This will prevent the screen handler from erasing part of the program when it sets-up the screen data region. When the channel is opened, two special options can be sent with the direction parameter (ICAX1). ICAX1 for screen open 7 6 5 4 3 2 1 0 ----------------- | C S W R | ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 C 1 = don't clear the screen S 1 = split screen R 1 = input W 1 = output Before the open command, the graphics mode number is placed into ICAX2. ICAX2 for screen open 7 6 5 4 3 2 1 0 ----------------- | : mode | ----------------- mode = $00 through $0B (0 - 11 (0 - 15 on XL/XE)) To open a channel to the screen in BASIC use the GRAPHICS command. BASIC screen open format GRAPHICS mode For Example: GRAPHICS 8 This will set up a mode 8 graphics screen and open channel 6 to it. If the graphics mode is 1 - 8, a split screen will be set up. For example, GRAPHICS 8 will set up a mode 8 screen with a four line text window at the bottom. If 16 is added to the mode number, a full screen will be set-up. For example, GRAPHICS 8+16 or GRAPHICS 24 will set up a mode 8 screen, with no text window, a full 192 pixels high. If the number 32 is added to the mode number, the screen will not clear when the channel opens. If you want to use a channel other than #6, you will have to use the open command. It is used in the following format. screen open without GRAPHICS command OPEN #channel,direction/special,mode,S: For example: OPEN #1,8,7,S: This will open channel 1 to a mode 7 screen for output only. For use of special parameters, see ICAX1 above. USING AN OPEN CHANNEL TO THE SCREEN Once a channel is opened to the screen it is used like any other input or output device. In other words, data is placed on the screen by the PRINT and PUT commands. Data is retrieved from the screen with the INPUT and GET commands. The part of the screen which the data will be put in or taken from is determined by the X,Y coordinants in the database variables COLCRS [$0055,2 (85)] and ROWCRS [$0054 (84)]. What appears on the screen depends on what graphics mode the computer is in. Before sending data to the screen in BASIC, a color register must be assigned to the data. Once a point is plotted on the screen, it's color will be determined by the color register it was assigned to. To assign a color to a ploted point, the COLOR command us used as follows. COLOR command format COLOR register For example, COLOR 1 After using the above command, all points plotted will be controlled by color register 1. To change color registers, use the COLOR command again. In assembly language, the color is determined by the data sent to the screen. See the above section on graphics modes for color information. In BASIC the PLOT command is used to put data on the screen. The PLOT command is used as follows. The BASIC PLOT command PLOT x,y x and y are the horizontal and vertical coordinates for the plotted point. In modes 3 through 11 a single point will be plotted. In modes 1 and 2 a text character will be printed on the screen by the PLOT command. The PRINT and PUT commands can also be used in basic. What appears on the screen depends on the graphics mode. In modes 1 and 2 the ATASCII characters sent to the screen will be printed just as in mode 0. See the paragraph on modes 1 and 2 above for more information. In the other modes what appears depends on how the ANTIC chip interprets the data bytes sent to the screen. For example, in mode 8, even numbered characters will be single pixels in color 1. Odd numbered characters will be in color 0 (background). There are two special commands for the screen handler, DRAW and FILL DRAW (ICCOM = $11 (17)) The draw command works exactly like the plot command except a straight line is drawn from the previous pixel to the new one. In BASIC it is used in the following format. the BASIC DRAW command DRAWTO x,y FILL (ICCOM = $12 (18)) Fill works like draw except the area to the right of the drawn line will be filled with the color in FILDAT [$02FD (765)]. The fill command expects to find a boundary to the right. If no boundary is found, the entire horizontal screen between the ends of the line is filled. To use the fill command in BASIC the XIO command must be used in the following format. POSITION x,y XIO 18 #6,0,0,"E:" Note that the cursor is first moved by the POSITION command. Below is an example of how to prepare for and use the fill command. using the fill command 2nd DRAWTO .____. DRAWTO here | | | | | | fill to here ! ! PLOT here This will draw and fill a box on the screen. THE COLOR REGISTERS There are nine bytes of memory which control the colors on the screen. These bytes are called color registers. The color registers have the following names and relationships. Color registers and relationships Register Register modes name address 0 & 8 1 & 2 3 5 7 4 & 6 9 & 11 10 HEX decimal COLOR numbers PCOLR0 $02C0 704 0 PCOLR1 $02C1 705 1 PCOLR2 $02C2 706 2 PCOLR3 $02C3 707 3 COLOR0 $02C4 708 0 - 63 1 1 4 COLOR1 $02C5 709 1 - 255 64 -127 2 5 COLOR2 $02C6 710 0 128-191 3 6 COLOR3 $02C7 711 192-255 7 COLOR4 $02C8 712 border backgnd 0 backgnd backgnd 8 The color numbers are in decimal. These are actually shadow registers. See the O.S. equates below for relationships. In modes 0 - 3 the COLOR number actually determines the character printed The register to which a pixel/character is assigned to is determined by the data byte sent to the screen through CIO. The data in the color registers in in the following format. Color register data format 7 6 5 4 3 2 1 0 ----------------- | color |bright | ----------------- color = one of 16 possible colors bright = one of 8 possible brightnesses (even numbers, 0 - E) In basic, the COLOR command is used to assign color registers. The corresponding registers depends on the graphics mode. For example, COLOR 0 is COLOR2 in mode 8. In most other modes COLOR 0 is COLOR4. See the above chart for the register relationships. To change the contents of the color registers in BASIC, the SETCOLOR command is used. In all modes except mode 10, the SETCOLOR command refers to the registers COLOR0 to COLOR4. SETCOLOR/register relationships SETCOLOR 0 COLPF0 (COLOR0) SETCOLOR 1 COLPF1 (COLOR1) SETCOLOR 2 COLPF2 (COLOR2) SETCOLOR 3 COLPF3 (COLOR3) SETCOLOR 4 COLBK (COLOR4) The format for the SETCOLOR command is... SETCOLOR command format SETCOLOR register,hue,brightness register = 0 - 4 (0 - 8 in mode 10) hue = 0 - 15 (16 colors) brightness = 0 - 16 (even numbers only (8 brightnesses) The following chart gives the colors represented by the hue number. colors represented by hue numbers 0 grey 8 blue 1 gold 9 cyan 2 gold-orange 10 blue-green 3 red-orange 11 blue-green 4 orange 12 green 5 magenta 13 yellow-green 6 purple-blue 14 yellow 7 blue 15 yellow-red The attract mode If a key is not pressed for more than 9 minutes the computer will enter the attract mode. This mode is used to prevent burning of the TV phosphors by lowering the brightness and constantly changing the colors. The attract mode timer, ATRACT [$004D (77)], is set to 254 ($FE) when the the attract mode is entered. To force the computer out of the attract mode, poke a number less than 127 into ATRACT. Useful database variables and OS equates APPMHI $000E,2 (14): lower limit for screen region ATRACT $004D (77): attract mode timer and flag LMARGN $0052 (82): left margin RMARGN $0053 (83): right margin ROWCRS $0054 (84): horizontal cursor position COLCRS $0055,2 (85): vertical cursor position DINDEX $0057 (87): current graphics mode SAVMSC $0058,2 (88): starting address of display buffer OLDROW $005A (90): previous cursor position OLDCOL $005B,2 (91): " " " OLDCHR $005D (93): character currently at the text cursor OLDADR $005E,2 (94): memory address of cursor RAMTOP $006A (106): end-of-RAM + 1 (MSB only) SDLSTL $0230,2 (560): shadow register of display list address TXTROW $0290 (656): text window cursor position TXTCOL $0291,2 (657): " " " " TXTMSC $0294,2 (660): starting address of text window data buffer RAMSIZ $02E4 (740): permanent end-of-RAM + 1 (MSB only) CRSINH $02F0 (752): cursor inhibit, 1 = no cursor FILDAT $02FD (765): color data for fill DSPFLG $02FE (766): if >0 screen control codes are displayed as ATASCII characters (EOL is uneffected) SSFLAG $02FF (767): > 0 = stop screen print COLPM0 $D012 (53266): actual color registers COLPM1 $D013 (53267): loaded from shadow COLPM2 $D014 (53268): registers during COLPM3 $D015 (53269): vertical blank COLPF0 $D016 (53270): COLPF1 $D017 (53271): see above COLPF2 $D018 (53272): for use COLPF3 $D019 (53273): COLBK $D020 (53274): OS shadow registers PCOLR0 $02C0 (704): COLPM0 PCOLR1 $02C1 (705): COLPM1 PCOLR2 $02C2 (706): COLPM2 PCOLR3 $02C3 (707): COLPM3 COLOR0 $02C4 (708): COLPF0 COLOR1 $02C5 (709): COLPF1 COLOR2 $02C6 (710): COLPF2 COLOR3 $02C7 (711): COLPF3 COLOR4 $02C8 (712): COLBK CHAPTER 9 THE RESIDENT DISK HANDLER The resident disk handler is separate from DOS and is part of the permanent operating system ROM. The disk handler does not use CIO. The resident disk handler works with one sector at a time. It is used by setting the drive number, sector number, and operation code in the device control block. The program then jumps (JSR) to the handler entry vector, DSKINV [$E453 (58451)]. Device control block (for resident disk handler) DDEVIC [$0300 (768)] Serial bus I.D. Set by handler DUNIT [$0301 (769)] Drive number DCOMND [$0302 (770)] Command byte DSTATS [$0303 (771)] status byte DBUFLO [$0304 (772)] DBUFHI [$0305 (773)] Pointer to 128 byte memory block for data storage. DTIMLO [$0306 (774)] Timeout value (response time limit) in seconds DBYTLO [$0308 (776)] DBYTHI [$0309 (777)] number of bytes transferred, set by handler DAUX1 [$030A (778)] DAUX2 [$030B (779)] sector number DISK HANDLER COMMANDS GET SECTOR Before the JSR to DSKINV is made the following parameters are set. GET SECTOR parameters DCOMND = $52 (82) DUNIT = (1 - 4) DBUFHI and DBUFLO = address of 128 byte buffer DAUX1 and DAUX2 = Sector number (LSB,MSB) This operation will read the specified sector and put the data into the specified buffer. PUT SECTOR PUT SECTOR is used the same as GET SECTOR except for DCOMND. PUT SECTOR parameters DCOMND = $50 (80) This operation sends the data in the specified buffer to the specified disk sector. PUT SECTOR WITH VERIFY PUT SECTOR WITH VERIFY is used the same as PUT SECTOR except for DCOMND. PUT SECTOR WITH VERIFY parameters DCOMND = $57 (87) This operation sends the data in the specified buffer to the specified disk sector then checks for errors. GET STATUS Only the DUNIT and DCOMND need to be set GET STATUS parameters DCOMND = $53 (83) DUNIT = (1 - 4) The status information will be put in three bytes starting at DVSTAT [$02EA (746)]. Status format 7 6 5 4 3 2 1 0 ----------------- DVSTAT + 0 | command stat | ----------------- + 1 | hardware stat | ----------------- + 2 | timeout value | ----------------- The command status byte gives the following information. Bit 0 1 = invalid command frame received 1 1 = invalid data frame received 2 1 = unsuccessful PUT operation 3 1 = disk is write protected 4 1 = active/standby The hardware status byte contains the status register of the ISN1771-1 disk controller chip. The timeout byte contains the maximum allowable response time for the drive in seconds. FORMAT DISK The handler will format then verify the the disk. The numbers of all bad sectors (up to 63) will be put into the specified buffer followed by two bytes of $FF. The following parameters are set before the call. FORMAT parameters DCOMND = $21 (33) DUNIT = (1 - 4) DBUFLO and DBUFHI = address of bad sector list (buffer) After the operation the status byte is set. Also, DBYTLO and DBYTHI will contain the number of bytes of bad sector information (not including the two $FF bytes). Useful data base variables and OS equates DVSTAT $02EA,3 (746): device status block, 3 bytes DDEVIC $0300 (768): serial bus I.D. DUNIT $0301 (769): device number DCOMND $0302 (770): command byte DSTATS $0303 (771): status byte DBUFLO $0304 (772): data buffer DBUFHI $0305 (773): pointer DTIMLO $0306 (774): timeout value DBYTLO $0308 (776): number of bytes transfered DBYTHI $0309 (777): DAUX1 $030A (778): sector DAUX2 $030B (779): number DSKINV $E453 (58451): disk handler entry vector CHAPTER 10 SYSTEM INTERRUPTS There are four types of interrupts which can occur with the 6502 microprocessor: 6502 interrupts 1. chip reset 2. IRQ, interrupt request (maskable) 3. MNI (non-maskable interrupt) 4. software interrupt (BRK instruction) CHIP RESET On the 400/800 the chip reset occurs only upon power-up and causes the computer to do a cold start. On later models, pressing [SYSTEM RESET] will cause a chip reset but the computer then does a warm start. On the 400/800, the [SYSTEM RESET] key generates a NMI interrupt. COLD START This is a synopsis of the cold start routine. 1 The warm start flag [$0008] is set to 0 (false) 2 If a cartridge slot contains a diagnostic cartridge, control is handed to the cartridge. 3 The end of RAM is determined by trying to complement the first byte of each 4K block of memory. 4 Hardware registers at $D000 - $D4FF (except $D100 - $D1FF) are cleared. 5 RAM is cleared from $0008 to the top of ram. 6 The user program jump vector, DOSVEC [$000A] is set to point to the black board mode (Atari logo display mode in XL/XE models). 7 The screen margins are set to 2 and 39 8 Interrupt vectors are initialized. 9 Bottom of free RAM pointer, MEMLO [$02E7], is set to point to $0700. 10 Resident CIO handlers are initialized. 11 If the [START] key is pressed the cassette boot request flag, CKEY [$004A], is set. 12 The CIO device table is initialized. 13 If a cartridge is present it is initialized. 14 Channel 0 is opened to the screen editor. The top-of-free-RAM pointer, MEMTOP [$02E5], is set to point below the screen region. The computer then waits for the screen to be established before continuing. 15 If the cassette boot flag is set the cassette is booted. 16 If there is no cartridge present or a cartridge doesn't prevent it, the disk is booted. 17 The cold start flag is reset. 18 If there is a cartridge present, the computer jumps to the cartridge's run vector. 19 If there is no cartridge present the computer jumps through the vector DOSVEC [$000A (10)]. DOSVEC will point to either a booted program, the memo pad routine (400/800) or the logo display routine (XL/XE). WARM START 1 The warm start flag is set to $7F (true). 2 cold start steps 2 - 4 are executed. 3 RAM is cleared from $0010 - $007F and $0200 - $03FF. 4 Cold start steps 7 - 14 are executed. 5 If cassette booted software is present the computer JSRs through CASINI [$0002]. 6 If disk booted software is present the computer JSRs through DOSINI [$000C (12)]. The difference between cold start and warm start is the condition of the warm start flag, WARMST, [$0008]. If this flag is 0 a complete cold start is executed. If the flag is anything other than 0 then only the warm start part of the warm start/cold start code is executed. NON-MASKABLE INTERRUPTS (NMI) NMI interrupts are generated by the following conditions: 1. Display list interrupt, generated by the ANTIC chip. 2. TV vertical blank interrupt, generated by the ANTIC chip. 3. [SYSTEM RESET] key (400/800). When an NMI interrupt occurs, the hardware register NMIST [$D40F] is examined to determine what type of interrupt occurred. The computer is then directed through the proper ram vector to service the interrupt. DISPLAY LIST INTERRUPTS (DLIs) The computer makes no use of DLIs. The ram vector points to an RTI instruction. VERTICAL BLANK INTERRUPTS (VBIs) There are two stages to the VBI service routine. The second stage is only done if a critical function was not interrupted. Stage 1 (VBI) The real time clock, RTCLOK [$0012 - $0014], is incremented. The attract mode variables are processed. System timer 1 is decremented. If it goes to zero the computer JSRs through system time-out vector 1. Stage 2 (VBI) The hardware registers are loaded with the data in their shadow registers. System timer 2 is decremented. If it goes to zero the computer JSRs through the system time-out vector 2. System timers 3, 4, and 5 are decremented. If a timer goes to zero the computer sets system timer flags 3, 4, and/or 5. If auto-repeat is active, the auto-repeat process is done. The keyboard debounce timer is decremented if not 0. Information at the controller port registers is read, processed and placed in the proper shadow registers. [SYSTEM RESET] INTERRUPT If a [SYSTEM RESET] interrupt is generated on the 400/800 the computer jumps to the warm start routine. INTERRUPT REQUESTS (maskable interrupts (IRQs)) When an IRQ interrupt occurs the hardware register IRQST [$D20E], the PIA status registers, PACTL [$D302] and PBCTL [$D303] are examined to determine what caused the interrupt. For each interrupt, the 6502 accumulator is pushed to the stack. The computer is then directed to the proper ram vector to service the interrupt. SOFTWARE INTERRUPT (BRK instruction) The operating system doesn't use software interrupts. The software interrupt vector points to a PLA followed by an RTI. Interrupt vectors Label address type function VDSLST $0200 NMI DLI Points to an RTI VVBLKI $0222 NMI stage 1 VBI VVBLKD $0224 NMI return-from-interrupt routine CDTMA1 $0226 NMI time-out 1 (used by SIO) CDTMA2 $0228 NMI time-out 2 (not used by OS) VPRCED $0202 IRQ not used (points to PLA,RTI) VINTER $0204 IRQ not used (PLA,RTI) VKEYBD $0208 IRQ keyboard interrupt VSERIN $020A IRQ used by Serial I/O routine VSEROR $020C IRQ used by SIO VSEROC $020E IRQ used by SIO VTIMR1 $0210 IRQ not used by OS (PLA,RTI) VTIMR2 $0212 IRQ not used by OS (PLA,RTI) VTIMR4 $0214 IRQ ? VIMIRQ $0216 IRQ main IRQ code VBREAK $0206 BRK unused by OS (PLA,RTI) SYSTEM TIMERS The following timers are updated during vertical blank (VBI) as noted above. If a timer is decremented to 0 the computer jumps through it's associated vector or sets it's associated flag. Label address flag/vector RTCLOK $0012 3 byte clock ($0012 = MSB) CDTMV1 $0218 CDTMA1 $0226 vector (SIO time-out) CDTMV2 $021A CDTMA2 $0228 vector CDTMV3 $021C CDTMF3 $022A flag CDTMV4 $021E CDTMF4 $022C flag CDTMV5 $0220 CDTMF5 $022E flag HARDWARE INTERRUPT CONTROL There are two registers on the antic chip which control interrupts. These registers can be used to disable interrupts if necessary. There are also two associated interrupt status registers. The IRQ enable and status registers use the same address. The result is that reading the register does not reveal the enabled interrupts but the interrupts pending. IRQ interrupt enable data should usually be written to the OS shadow first. Reading the OS shadow tells which interrupts are enabled. Non maskable interrupt enable NMIEN $D40E 7 6 5 4 3 2 1 0 ----------------- | | | not used | ----------------- bit 7 1 = DLI enabled 6 1 = VBI enabled Non maskable interrupt status NMIST $D40F 7 6 5 4 3 2 1 0 ----------------- | | | | not used| ----------------- bit 7 1 = DLI pending 6 1 = VBI pending 5 1 = [SYSTEM RESET] key pending Interrupt request enable IRQEN $D20E 7 6 5 4 3 2 1 0 ----------------- | | | | | | | | | ----------------- bit 7 1 = [BREAK] key interrupt enable 6 1 = keyboard interrupt enable 5 1 = serial input interrupt enable 4 1 = serial output interrupt enable 3 1 = serial output-finished interrupt enable 2 1 = timer 4 interrupt enable 1 1 = timer 2 interrupt enable 0 1 = timer 1 interrupt enable IRQEN has a shadow register, POKMSK [$0010 (A)]. Interrupt request status IRQST $D20E 7 6 5 4 3 2 1 0 ----------------- | | | | | | | | | ----------------- bit 7 1 = [BREAK] key interrupt pending 6 1 = keyboard interrupt pending 5 1 = serial input interrupt pending 4 1 = serial output interrupt pending 3 1 = serial output-finished interrupt pending 2 1 = timer 4 interrupt pending 1 1 = timer 2 interrupt pending 0 1 = timer 1 interrupt pending WAIT FOR HORIZONTAL SYNC Writing any number to WSYNC [$D40A (54282)] will cause the computer to stop and wait for the next TV horizontal sync. It is wise to use DLIs one TV line before needed then writing to WSYNC. This will keep other interrupts from causing DLIs to be serviced late. This can cause a DLI to change something in the middle of a scan line. Useful database variables and OS equates POKMSK $0010 (16): IRQEN shadow IRQEN $D20E (53774): enables IRQs when written to IRQST $D20E (53774); gives IRQs waiting when read PACTL $D302 (54018): bit 7 (read) peripheral A interrupt status bit 0 (write) peripheral A interrupt enable PBCTL $D303 (54019): bit 7 (read) peripheral B interrupt status bit 0 (write) peripheral B interrupt enable WSYNC $D40A (54282): wait for horizontal sync NMIEN $D40E (54286): NMI enable NMIST $D40F (54287): NMI status CHAPTER 11 THE FLOATING POINT ARITHMETIC PACKAGE The routines which do floating point arithmetic are a part of the operating system ROM. The Atari computer uses the 6502's decimal math mode. This mode uses numbers represented in packed Binary Coded Decimal (BCD). This means that each byte of a floating point number holds two decimal digits. The actual method of representing a full number is complicated and probably not very important to a programmer. However, for those with the knowledge to use it, the format is given below. Floating point number representation byte 0 xx excess 64 exponent + sign xx \ xx \ xx > 10 BCD digits xx / byte 7 xx / The decimal point is shifted to left of the MSD and the exponent is adjusted accordingly. Therefore, the decimal point doesn't need to be represented. For programming purposes, floating point numbers can be in ASCII code. It takes up to 14 bytes to store a floating point number in this manner. The floating point package has a routine to convert numbers between ASCII and floating point. USE OF THE FLOATING POINT PACKAGE The floating point package has several routines to convert between ASCII and FP and to do the arithmetic functions. These are the important data base variables. Floating point data base variables FR0 $00D4,6 (212): 6 byte buffer for floating point number FR1 $00E0,6 (224): 6 byte buffer for floating point number CIX $00F2 (242): index for INBUFF address INBUFF $00F3,2 (243): 2 byte pointer to ASCII floating point number FLPTR $00FC,2 (252): 2 byte pointer to user buffer for floating point number LBUFF $0580,? (1408): result buffer for FASC routine MAKING THE CALL To do a floating point function, first set the proper pointers and JSR to the operation entry point. Below is a list of the entry points and parameters. ASCII to floating point Converts ASCII representation pointed to by INBUFF to FP in FR0. AFP = $D800 INBUFF = address of ASCII number CIX = buffer offset if any JSR AFP FLOATING POINT TO ASCII Converts floating Point number in FR0 to ASCII. The result will be in LBUFF. INBUFF will point to the ASCII number which will have the bit 7 of the last byte set to 1. FASC = $D8E6 JSR FASC INTEGER TO FLOATING POINT CONVERSION. Converts a 2 byte unsigned integer (0 to 65535) in FR0 to floating point in FR0. IFP = $D9AA JSR IFP FLOATING POINT TO INTEGER CONVERSION. Converts floating point number in FR0 to 2 byte integer in FR0. FPI = $D9D2 JSR FPI BCS overflow ADDITION Adds floating point numbers in FR0 and FR1 with result in FR0. FADD = $DA66 JSR FADD BCS out of range SUBTRACTION subtracts FR1 from FR0 with the result in FR0. FSUB = $DA60 JSR FSUB BCS out of range MULTIPLICATION Multiplies FR0 by FR1 with the result in FR0. FMUL = $DADB JSR FMUL BCS out of range DIVISION Divides FR0 by FR1 with result in FR0. FDIV = $DB28 JSR FDIV BCS out of range or divisor is 0 LOGARITHMS Puts logarithm of FR0 in FR0 LOG = $DECD LOG10 = $DED1 JSR LOG ;for natural log. or JSR LOG10 ;for base 10 log. BCS negative number or overflow EXPONENTIATION Put exponentiation of FR0 in FR0 EXP = $DDC0 EXP10 = $DDCC JSR EXP ;for e ** Z or JSR EXP10 ;for 10 ** Z POLYNOMIAL EVALUATION Puts the result of an n degree polynomial evaluation of FR0 in FR0. PLYEVL = $DD40 LDX LSB of pointer to list of floating point coefficients, ordered high to low. LDY MSB of above LDA number of coefficients in list JSR PLYEVL BCS overflow CLEAR FR0 Sets FR0 to all zeroes ZFR0 = $DA44 JSR ZFR0 CLEAR ZERO PAGE FLOATING POINT NUMBER Clears user floating point number in page zero. ZF1 = $DA46 LDX address of zero page FP buffer JSR ZF1 LOAD FR0 WITH FLOATING POINT NUMBER Loads FR0 with user FP number in buffer pointed to by 6502 X and Y registers or by FLPTR. After either operation below, FLPTR will point to the user FP buffer. FLD0R = $DD89 LDX lsb of pointer LDY msb JSR FLD0R or FLD0P = $DD8D FLPTR = address of FP number JSR FLD0P LOAD FR1 WITH FLOATING POINT NUMBER Loads FR1 with user FP number in buffer pointed to by 6502 X and Y registers or by FLPTR. After either operation below, FLPTR will point to the user FP buffer. FLD1R = $DD98 LDX lsb of pointer LDY msb JSR FLD1R or FLD1P = $DD9C FLPTR = address of FP number JSR FLD1P STORE FR0 IN USER BUFFER stores the contents of FR0 in user FP buffer pointed to by 6502 X and Y registers or by FLPTR. After either operation below, FLPTR will point to the user FP buffer. FST0R = $DDA7 LDX lsb of pointer LDY msb JSR FST0R or FST0P = $DDAB FLPTR = address of FP number JSR FST0P MOVE FR0 TO FR1 Moves the contents of FR0 to FR1 FMOVE = $DDB6 JSR FMOVE The usual use sequence of the floating point package might be to: load FR0 and FR1 with FP numbes from user specified buffers do the math then store FR0 in a user buffer. An alternative might be to: convert an ASCII representation to FP (the result is automatically in FR0). move FR0 to FR1. Convert the second ASCII number. Do the math. Convert FR0 back to ASCII. Store the number back into a user buffer. The floating point package uses the following blocks of RAM. RAM used by floating point package $00D4 - $00FF $057E - $05FF If the floating point package is not used the above ram is free. Useful data base variables and OS equates FR0 $00D4,6 (212): system FP buffer FR1 $00E0,6 (224): system FP buffer CIX $00F2 (242): INBUFF index INBUFF $00F3,2 (243): pointer to ASCII FP buffer FLPTR $00FC,2 (252): pointer to user FP buffer LBUFF $0580 (1408): result buffer for FP to ASCII AFP $D800 (55296): ASCII to FP FASC $D8E6 (55526): FP to ASCII IFP $D9AA (55722): integer to FP FPI $D9D2 (55762): FP to integer ZFR0 $DA44 (55876): clear FR0 ZF1 $DA46 (55878): clear zero page FP buffer FSUB $DA60 (55904): FR0 - FR1 FADD $DA66 (55910): FR0 + FR1 FMUL $DADB (56027): FR0 * FR1 FDIV $DB28 (56104): FR0 / FR1 FLD0R $DD89 (56713): load FR0 by X,Y pointer FLD0P $DD8D (56717): load FR0 by FLPTR pointer FLD1R $DD98 (56728): load FR1 by X,Y pointer FLD1P $DD9C (56732): load FR1 by FLPTR pointer FST0R $DDA7 (56743): store FR0 at buffer by X,Y pointer FST1P $DDAB (56747): store FR0 at buffer by FLPTR pointer FMOVE $DDB6 (56758): move FR0 to FR1 EXP $DDC0 (56768): e exponentiation EXP10 $DDCC (56780): base 10 exponentiation PLYEVL $DD40 (56640): polynomial evaluation LOG $DECD (57037): natural log of FR0 LOG10 $DED1 (57041): base 10 log of FR0 CHAPTER 12 Boot software formats There are three ways which programs may be booted (loaded automatically upon power-up): From the disk drive From the cassette recorder From a ROM cartridge DISK BOOTED SOFTWARE The disk drive is the primary source for programs (other than the BASIC interpreter in the computer ROM). A program booted from disk must be a machine language program. Secondly, the program is arranged on disk in a different manner from the DOS files. When the computer is first turned on, it will attempt to read a program starting at sector one in disk drive one. The exceptions are, if a cartridge prevents the disk boot process or the [START] key is pressed. The program is expected to use all 128 bytes of each sector. FORMAT OF A DISK BOOTED PROGRAM A disk booted program begins at sector one on the disk and continues in sequence. The first six bytes of the first sector contain program information. The rest of the bytes contain the program itself. Disk boot program header 1st byte $00 flags, stored in DFLAGS [$0240] $xx number of sectors used by program $xx address to start load $xx $xx initialization address 6th byte $xx 7th byte $xx start of program The flags byte is usually unused and should be zero. The load address is stored in BOOTAD [$0242,2 (578)]. The initialization address is stored in DOSINI [$000C,2 (12)]. After the program is completely loaded the computer will JSR to the address stored in DOSINI for initialization. It will then jump to the address stored in DOSVEC to run the program. The initialization part of the program should set the bottom-of-free-RAM pointer, MEMLO [$02E7,2 (743)], to point to the end of the program + 1. This will protect the program from the computer and other programs. The top-of-user-RAM pointer, APPMHI [$000E,2 (14)], is also usually set to point to the same address. This will protect the program from the video hardware. It must also set DOSVEC [$000A,2 (10)] to actually point to the run address of the program. The initialization should of course end with and RTS. With DOSINI and DOSVEC properly set, the program will restart up pressing the [SYSTEM RESET] key. Rmember that the load address of the program should be six bytes before where you want the program to reside in memory. The six byte header will load at the specified start address followed by the program. CASSETTE BOOTED SOFTWARE The cassette boot process is nearly identical to the disk boot process. The processes are so similar that cassette boot programs can usually be transferred directly to disk and vice-versa. The two differences are: The cassette is booted instead of the disk if the [START] key is pressed when the power is turned on. A bug in early operating systems requires the booted program to turn off the cassette motor with the following command. LDA #$3C STA PACTL [$D302] CARTRIDGE BOOTED SOFTWARE The Atari 800 has two cartridge slots. All other models have only one. The second cartridge slot, slot B on the 800, resides from $8000 to $9FFF. The first slot, slot A, resides from $A000 to BFFF. If a cartridge is inserted in a slot it will disable any RAM in the same area. Slot A, which is present in all models, can reside at the entire 16K used by both cartridges in the 800 ($8000 to $BFFF). Cartridges use the last six bytes for boot information. In cartridge A these bytes are from $BFFA to $BFFF. In cartridge B they are from $9FFA to 9FFF. last six bytes of a cartridge $9FFA or $BFFA xx start address xx 00 xx flag byte xx init address $9FFF or $BFFF xx Flag byte bit 0 1 = allow disk boot bit 2 0 = do not start cartridge after init bit 7 1 = cartridge takes control before OS is initialized The initialization process for the cartridge should be similar to that for disk and cassette. A minimum of an RTS instruction is required. The third byte of the cartridge tailer is used by the OS to check for the presence of a cartridge. This byte must be zero. A 16K cartridge will use both cartridge areas and the cartridge B tailer area can be used for program code. THE CARTRIDGE HARDWARE Most cartridges consist of two ROM chips on a single circuit board. Moreover, both chip sockets have identical pin assignments. In other words, the chips can be switched to opposite sockets and the cartridge will still work. The difference is in the chips themselves. On one chip, the A12 pin acts as an active-low chip select. On the other the A12 pin acts as an active-high chip select. Therefore the state of the A12 pin selects between the two chips. Cartridge slot pin assignments BACK 111111 543210987654321 --------------- --------------- SRPNMLKJHFEDCBA FRONT 1 1 = 16K A A13 (16K only) 2 A3 B GND 3 A2 C A4 4 A1 D A5 5 A0 E A6 6 D4 F A7 7 D5 H A8 8 D8 J A9 __ 9 D1 K A12 (CS)/(CS) 10 D0 L D3 11 D6 __ M D7 12 (CS) N A11 13 +Vcc P A10 14 +Vcc R NC 15 NC S NC The BASIC interpreter resides in the memory used by cartridge A. In 400, 800 and 1200XL models, a BASIC cartridge is required to run BASIC programs. On other XL and XE models, inserting a cartridge into the slot or pressing the [OPTION] key upon power-up will disable the internal BASIC ROM. If BASIC is disabled without inserting another cartridge, the area from $A000 to $BFFF will contain RAM. Useful data base variables and OS equates APPMHI $000E,2 (14): low limit of screen region DOSVEC $000A,2 (10): run and program reset vector DOSINI $000C,2 (12): init and reset init CARTB $8000 (32768): start of cartridge B CARTA $A000 (40960): start of cartridge A PACTL $D302 (54018): port A control register Bit 3 controls the cassette motor CHAPTER 13 THE SERIAL INPUT/OUTPUT INTERFACE (SIO) Most input and output with the Atari computer passes through the serial I/O bus. The SIO interface is rather complicated but you are unlikely to need to use it directly. CIO usually handles SIO for you. However, if you want to design your own I/O device and it's associated handler, you need to know how to use the SIO. SIO transfers data at a rate of 19,200 baud on separate input and output lines. The data is sent one byte at a time, LSB first, in an asynchronous format. There are also clock-in and clock-out lines. There is a signal on the clock-out line but it is not used by any present devices. The clock-in line is available for synchronous transfer but is not used by the OS. The signal on the clock-out line goes high at the leading edge of each bit and goes low in the middle of each bit. One byte of SIO data +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | | | | | | | | | | | | | | | | clock -------------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +------ ---------+ +---+ +-------+ +-------- | 0 | 1 | 0 | 1 1 | 0 0 | 1 data +-------+ +---+ +-------+ | | start bit stop bit The SIO interface is used much like the resident disk handler. In fact, it uses the same device control block as the resident disk handler. After the control block parameters are set, a JSR is made to the SIO entry vector, SIOV, at $E459 (58457). Device control block (for SIO) DDEVIC [$0300 (768)] Serial bus I.D. Set by handler or program. DUNIT [$0301 (769)] Device number if more than one. DCOMND [$0302 (770)] Device command byte. DSTATS [$0303 (771)] Before the SIO call, this byte tells whether the operation is read, write or that there is no data transfer associated with the command. After the call this byte will hold the status (error/no error code) of the operation. DSTATS format before command 7 6 5 4 3 2 1 0 ----------------- |W|R| not used | ----------------- If both W and R are 0, there is no data transfer. DBUFLO [$0304 (772)] DBUFHI [$0305 (773)] Points to the data buffer for either input or output. DTIMLO [$0306 (774)] Timeout value (response time limit) in 64/60ths of a second to be set by handler or program. DBYTLO [$0308 (776)] DBYTHI [$0309 (777)] Number of bytes to be transferred, set by handler or program. This parameter is not required if the DSTATS specifies no data transfer. DAUX1 [$030A (778)] DAUX2 [$030B (779)] These parameters are sent to the device as part of the command frame. USING THE SIO INTERFACE All commands on the serial bus must originate from the computer. The peripherals will present data on the bus only when commanded to do so. Any operation on the serial bus begins with a five byte command frame. While the command frame is being sent, the command line of the serial connector is 0. Command frame format $xx DDEVIC $xx DCOMND $xx DAUX1 $xx DAUX2 $xx checksum The first four bytes of the command frame come from the device control block. the checksum is the sum of the other four bytes with the carry added back after each addition. If both R and W of the DSTATS are 0, no data is sent to, or expected from the peripheral, after a command frame is sent. However, the device is usually expected to send an ACK byte ($41) after the command frame is sent. If the command frame is invalid, an NAK byte ($4E) should be sent. If the operation is output (W = 1) the computer will send a data frame after it receives the ACK of the command frame. It then expects an ACK after the data frame is sent. If the operation is an input (R = 1) the computer expects a data frame from the peripheral after the ACK. With either input or output, a "complete" code ($43) should be sent to the computer when the operation is finished. The "complete" code would follow the ACK of the data frame with an output operation. If the operation is not completed for some reason, the peripheral should send an error code ($45) instead of "complete". SIO data frame byte 1 $xx\ > data bytes byte n $xx/ byte n+1 $xx checksum SIO commands READ $52 WRITE $57 STATUS $53 PUT $50 FORMAT $21 DOWNLOAD $20 READADDR $54 READ SPIN $51 MOTOR ON $55 VERIFY SECTOR $56 Present SIO device I.D.s DISK $31 - $34 (D1 - D4) PRINTER $40 RS-232-C $50 - $53 (R1 - R4) THE SERIAL CONNECTOR The serial connectors on the computer and all peripherials are identical. Nearly all peripherials have two serial connectors. Either connector may be used for any connection. The serial bus is designed so that peripherials can be daisy-chained together. The following is a diagram of the serial connector. The serial connector pin-out 1 1 2 4 6 8 0 2 ----------- /o o o o o o\ /o o o o o o o\ ----------------- 1 3 5 7 9 1 1 1 3 1 clock in (to computer) 2 clock out 3 data in 4 GND 5 data out 6 GND 7 command (active low) 8 cassette motor control 9 proceed (active low) 10 +5V/ready 11 audio in 12 +12V (400/800) 13 interrupt (active low) Proceed goes to pin 40 (CA1) of the PIA. It is not used by present peripherials. Interrupt goes to pin 18 (CB1) of the PIA. It is not used by present peripherials. Pin 10 doubles as a 50mA +5V peripharal power supply and a computer ready signal. Useful database variables and OS equates SIOV $E459 (58457): serial port handler entry DDEVIC $0300 (768): device ID DUNIT $0301 (769): device number DCOMND $0302 (770): command byte DSTATS $0303 (771): status byte DBUFLO $0304 (772): data buffer pointer DBUFHI $0305 (773): DTIMLO $0306 (774): timout value DBYTLO $0308 (776): number of bytes to transfer DBYTHI $0309 (777): DAUX1 $030A (778): sent to device DAUX2 $030B (779): sent to device CHAPTER 14 THE HARDWARE CHIPS The previous chapters described the operating system of the computer. The following chapters will examine the hardware which supports the 6502 and the hardware's associated software. THE GTIA CHIP The GTIA (George's Television Interface Adapter) is the main video circuit in the computer. It controls the following functions. GTIA functions Priority of overlapping objects Color and brightness, including information from the antic chip. Player/missile control. console switches and game control triggers. THE ANTIC CHIP The main job of the ANTIC chip is interpreting the display buffer for the GTIA chip. The ANTIC chip is somewhat of a processor in it's own right. The program which runs it is called the display list and usually resides just before the display buffer in memory. The ANTIC chip operates independent of the 6502. It operates by direct memory access (DMA). The ANTIC chip gives a HALT signal the 6502, causing the 6502 to give up control of the address bus. The ANTIC chip can then read any data it needs to from memory. ANTIC chip functions DMA (Direct Memory Access) control. NMI (Non-Maskable Interrupt) control. LIGHT PEN READING WSYNC (wait for horizontal sync) THE POKEY CHIP The most important jobs of the POKEY chip are reading the keyboard and operating the serial port. It also has the following functions. POKEY chip functions Keyboard reading. Serial port. Pot (game paddles) reading. Sound generation. System timers. IRQ (maskable interrupt) control. Random number generator. THE PIA CHIP The PIA (Parallel Interface Adapter) is a commonly used I/O chip. It consists of two 8 bit parallel ports with hand shaking lines. In the Atari, it has the following functions. Game controller port control (bi-directional). Peripheral control and interrupt lines. Registers in the hardware chips are treated as memory addresses. Many of the registers are write only. These registers cannot be read from after they are written to. Other registers control one function when written to and give the status of an entirely different function when read from. Still other registers are strobes. Any command which causes the address of one of these registers to appear on the address bus will cause their functions to be performed. The write only registers have shadow registers in RAM. Data to be put in the registers is usually put into the shadow registers. The data in the shadow registers is automatically moved to the operating registers during vertical blank. For register use and address, see the previous chaptes on the associated functions. CHAPTER 15 DISPLAY LISTS [some of this file was lost...] chip also has a memory scan counter. This register scans the display buffer for data to be interpreted and displayed. Once loaded, the memory scan counter's 4 most significant bits are fixed. The result is that the memory scan counter cannot cross a 4K memory boundary (i.e. $AFFF to $B000) without being reloaded. DISPLAY LIST INSTRUCTIONS There are three basic instructions in the display list. The type of instruction is determined by bits 0,1,2 and 3 of an instruction byte. The other four bits give auxilliary parameters for the instruction. Bit 7 always enables a display list interrupts (DLIs). Display list instruction format 7 6 5 4 3 2 1 0 ----------------- |I|n|n|n|0|0|0|0| ----------------- \ / \ / --- ------ | | | 0 = display blank lines | 0-7 = number of blank lines (1-8) 7 6 5 4 3 2 1 0 ----------------- |I|W| | |0|0|0|1| ----------------- | \ / | ------ | | | 1 = jump (3 byte instruction) | 0 = jump and display one blank line 1 = jump and wait for vertical blank 7 6 5 4 3 2 1 0 ----------------- |I|R|H|V|M|M|M|M| ----------------- | | | | \ / | | | | ------ | | | | | | | | | 2-F = display one line of graphics in | | | | ANTIC mode 2-F | | | 1 = horizontal scroll enabled | | | | | 1 = vertical scroll enabled | | | 1 = reload memory scan counter with next two bytes | 1 = display list interrupt, all instructions In the display instruction, the ANTIC mode is different from the CIO graphics mode. However, each CIO graphics mode uses a particular ANTIC mode. Below are descriptions of the ANTIC modes with their associated graphics (CIO) modes. ANTIC MODE 2 (Graphics 0) Uses 8 pixel by 8 pixel characters, 40 characters horizontal, 8 TV scan lines vertical. Only one color can be displayed at a time. ANTIC MODE 3 8 X 10 pixel, Graphics 0 type characters. This mode requires a custom character set. The advantage is that it allows true decenders. The custom C-set is still 8 X 8 pixels. Lower-case letters with decenders have the bottom row of pixels put on the top row. Lower-case "y" for ANTIC mode 3 C-set Display ---------- ---------- | XXXXX | | | | | | | | | | | | XX XX | | XX XX | | XX XX | | XX XX | | XX XX | | XX XX | | XXXXX | | XXXXX | | XX | | XX | ---------- | XXXXX | | | ---------- ANTIC MODE 4 (graphics 12 on XL and XE) This mode has characters the same size as graphics 0. However, the characters are only 4 X 8 pixels. This gives only half the horizontal resolution of graphics 0. The advantage is that up to four colors of "graphics 0" characters can be displayed at once. This mode also requires a custom C-set. Below is a comparison of the normal C-set to one which works with the ANTIC 4 mode. Upper-case "A" for ANTIC modes 2 and 4 mode 2 mode 4 ---------- ---------- | | | | | XX | | yy | | XXXX | | yy | | XX XX | |xx zz | | XX XX | |xx zz | | XXXXXX | |xxyyzz | | XX XX | |xx zz | | | | | ---------- ---------- xx, yy and zz represent two bit binary numbers, controlling one pixel each. These numbers determine which color register a pixel is assigned to: (COLOR0, COLOR1, COLOR2 or COLOR3). ANTIC mode 5 Antic mode five is identical to ANTIC mode 4 except the characters are displayed twice as tall. This makes only 12 lines on the screen. ANTIC MODE 6 (Graphics 1) This mode uses 8 X 8 pixel characters except they are displayed twice as wide as in ANTIC mode 2. There are 3 colors available at once but only one case (upper or lower) can be displayed at a time. The data base variable CHBAS [$02F4 (756)] controls the character, [$E0 (224) = upper-case, $E2 (226) = lower-case] The color/character is controlled by either the color statement or the ATASCII number of the character printed. Control characters are controlled by COLOR0, upper-case characters by COLOR1 and lower-case characters by COLOR2. Remember that all characters print as upper-case alpha characters, but of different colors. ANTIC MODE 7 (Graphics 2) This mode is identical to mode 6 except the characters are displayed twice as tall. This results in only 12 lines possible on the screen. ANTIC MODE 8 (Graphics 3) This is the first graphics (non-character) mode. This mode, as other non-character graphics modes do, uses data in the display buffer as a bit map to be displayed. A command to display in mode 8 will cause the ANTIC chip to read the next 10 bytes in the display buffer. Each pair of bits will control one pixel as in mode 4. However, the pixels are blocks the same size as a Graphics 0 (ANTIC 2) characters. ANTIC MODE 9 (Graphics 4) This is similar to ANTIC mode 8 except each byte controls 8 pixels (instead of 4) and only one color can be displayed at a time. The pixels are also half the size of those in ANTIC mode 8. ANTIC MODE A (Graphics 5) This mode uses 20 bytes per line/command. As in ANTIC mode 8, each pair of bits controls one pixel. The result is that the pixels are the same size as in ANTIC mode 9 but four colors can be displayed at once. ANTIC MODE B (Graphics 6) As in mode A, there are 8 pixels per byte and only one color. The pixels are half the size as in mode A. ANTIC MODE C Like mode B except the pixels are half as tall (only one T.V. line). ANTIC MODE D (Graphics 7) 40 Bytes per line, each byte controls 4 pixels. The pixels are 1/4 as large as in ANTIC mode 8 (Graphics 3). ANTIC MODE E (Graphics 15 on XL and XE) Like mode D except the pixels are half as tall (one T.V. line). Antic mode E is sometimes called Graphics 7.5 ANTIC mode F (Graphics 8, 9, 10 and 11) This is the highest resolution mode. Pixels are 1/8 the size of ANTIC mode 8 or mode 2 characters. It uses 40 bytes per line, each byte controlling 8 pixels, unless the GTIA chip intervenes. Only one color can be displayed at a time. DISPLAY LIST EXAMPLES When CIO opens a channel to the screen, it sets up the proper display list for the ANTIC chip. The following are the things CIO must handle when setting up the display list. Display list duties as used by CIO display a certain number of blank lines at the top of the screen. Load the memory scan counter with the address of the display data buffer. Display the required number of lines in the required ANTIC mode. Set up a jump instruction if the display list crosses a 1K memory boundary. Set up a reload-memory-scan-counter instruction if the display data buffer crosses a 4K memory boundary. CIO assumes that the display data buffer will butt against an 8K memory boundary. If a program causes the display buffer to cross a 4K boundary (by changing RAMTOP [$006A (106)] to point to an address which is not at an 8K boundary) the screen will be scrambled. This is not usually a problem if the graphics mode doesn't require a large block of memory. SAMPLE DISPLAY LIST Below is an example of a Graphics 0 display list as CIO would set it up. Display list for Graphics 0 assuming BASIC starts at $A000 address instruction explanation Dec. Hex. $9C20 112 $70 \ 112 $70 >---- 24 blank lines (8 each command) 112 $70 / 66 $42 ----- load memory scan counter with $9C24 64 $40 \__ next two bytes and display one line 156 $9C / \ of ANTIC 2 characters 2 $02 -\ | 2 $02 | \- address of display data buffer 2 $02 | 2 $02 \--- 2nd ANTIC 2 instruction - --- 2 $02 ----- 24th ANTIC 2 instruction 65 $41 \ 32 $20 >---- jump back to start of list 156 $9C / $9C40 ??? ?? first byte of display data buffer --- -- $9FFF ??? ?? last byte of buffer $A000 start of ROM A display list for a higher resolution graphics mode would require more instructions and might cross a 1K boundary. It would then include a jump instruction to cross the boundary. MULTIPLE DISPLAYS It is possible to set up multiple displays and use one at a time. The technique of changing from one display to another is called page flipping. Below is the simplest way to set up two displays. setting up two displays Call a graphics mode through CIO or by using a BASIC GRAPHICS command. Store the display list pointers, SDLSTL and SDLSTH, and the CIO screen pointer, SAVMSC [$0058,2 (88)]. Move the start-of-ROM pointer, RAMTOP [$006A (106)] to below the current display list. RAMTOP is a one byte pointer so it changes in increments of one page (256 bytes). make another graphics call as in the first step. store the new display list pointer and CIO screen pointer. This will set up two displays, each with it's own display list. If the displays are in the same graphics mode, or you will not make any changes in the displays with CIO commands, (PLOT, PRINT, etc.) you can flip between the two simply by changing the display list pointer. If the screens are in the same graphics mode and you want to change which one to do CIO commands to, Change the CIO screen pointer, SAVMSC [$0058,2 (88)]. This way, you can display one screen while drawing on the other. If you want to do CIO commands to screens of different graphics modes, you will have the move RAMTOP and do a graphics call to change screens. If your manipulation of RAMTOP causes the display data buffer to cross a 4K boundary, the screen may be scrambled. DISPLAY LIST INTERRUPTS DLIs are not used by the operating system. However, other programs can initiate and use them. Use the following steps to set up display list interrupts. Setting up DLIs Set bit 7 of the display list instruction for the line before you want the interrupt to occur. (The interrupt routine should set WSYNC and wait for the next line to execute.) Set bit 7 of NMIEN [$D40E (54286)] to enable DLIs. Set the DLI routine vector, VDSLST [$0200,2 (512)] to point to your machine language DLI routine. Your DLI routine should set WSYNC [$D40A (54282)]. STA WSYNC will do. THis will cause the 6502 to wait for the next horizontal sync. This will keep the DLI routine from changing something in the middle of a T.V. line. The DLI routine must end with an RTI instruction. SCROLLING Scrolling is controlled by a combination of scroll position registers, and changing the memory scan counter. Basically, course scrolling is done by reloading the memory scan counter and fine scrolling is done by changing the scroll registers. VERTICAL SCROLLING Vertical scrolling is very simple. Follow the steps below to set up vertical scrolling of graphics. Steps to use vertical scrolling Set bit 4 of the first byte of the display list instruction for each line to be scrolled. Put the number of T.V. lines to offset the graphics vertically in the vertical scroll register, VSCROL [$D405 (54277)] The vertical scroll register can offset the graphics upward by 0 - 7 T.V. lines in the 24 line graphics modes (ANTIC modes 2 and 4). In 12 line graphics modes (ANTIC modes 5 and 7) it can vertically offset the graphics by 0 - 15 T.V. lines. To offset the graphics an 8th (or 16th) line, the scroll register is reset to 0 and the memory scan counter is reloaded with the address of the next line of graphics in the display data buffer. If the entire screen is being scrolled, the load-memory-scan-counter command (near the beginning of the display list) is changed to point to the address of the second line of graphics. HORIZONTAL SCROLLING Horizontal scrolling works much like vertical scrolling. It is enabled by setting bit 5 of the instruction for each line to be scrolled. The horizontal scroll register, HSCROL [$D404 (54276)], sets the offset. The small difference is that graphics are moved twice as far per change (two graphics 8 pixels instead of one). Also, when HSCROL = 0 the graphics are offset beyond the left edge of the screen by 16 color clocks (32 Graphics 8 pixels). When HSCROL = 15, the graphics line is shifted one color clock (2 Graphics 8 pixels) to the left of the screen. The big difference is that the memory scan counter gets messed up. This means that you must use a reload-memory-scan-counter command for each line of graphics. This is a major modification of the display list. It will require you to move and build the list yourself. The advantage of this is that you can have a scrolling window in a large graphics map. The technique is to move the window by reloading the memory scan counter, then fine scrolling to the invisible bytes beyond the edges of the screen. useful data base variables and OS equates SAVMSC $0058,2 (88): pointer to current screen for CIO commands RAMTOP $006A (106): start-of-ROM pointer (MSB only) VDSLST $0200,2 (512): DLI vector RAMSIZ $02E4 (740): permanent start-of-ROM pointer (MSB only) DLISTL $D402 (54274): display list pointer low byte DLISTH $D403 (54275): " high byte HSCROL $D404 (54276): horizontal scroll register VSCROL $D405 (54277): vertical scroll register NMIEN $D40E (54286): NMI enable (DLIs) Shadow registers SDLSTL $0230 (560): DLISTL SDLSTH $0231 (561): DLISTH CHAPTER 16 PLAYER AND MISSILE (PM) GRAPHICS Players and missiles (called sprites on some computers) are movable objects which are independent of the normal graphics. Player and missile graphics are fairly straight forward. Once the computer is set-up for PM graphics, five 8-pixel-wide columns can be displayed on the screen. The horizontal resolution (width of each pixel) and the vertical resolution (number of scan lines per pixel) are variable. The horizontal position of each column is determined by it's horizontal position register. Each column is simply a representation of a bit map in a certain block of memory. If you want to draw an object on the screen, you simply put a bit map representing it in the proper memory block. The vertical position of an object is determined by the location of it's bit map in memory. For example, if you want to draw a happy face in the middle of the screen, you put a happy face bit map in the middle of one of the memory blocks controlling one of the columns. One column (player) displayed on the screen ---------- first byte of a block | | | | ------------------------------ | | | | | | | | | | | | | | | | | | | | | | | | | | ++++ | visible | | | + + | | | |+ + + +| | | |+ +| area | | |++ ++| | | |+ ++++ +|--object | | | + + | bit map | | | ++++ | | | | | | | | | | | | | | ------------------------------ | | | | ---------- last byte of a block Horizontal positions $00 $30 $CE $FF (0) (48) (206) (255) | | | | | Left edge right edge | | | Far left far right To move the happy face vertically you would move the entire bit map in memory. To move the happy face horizontally you change the number in the horizontal position register for the proper player. One of the players can be (and often is) split into four columns of two pixels wide each. These columns are then called missiles. In this case, each missile has it's own horizontal position register. SETTING UP PM GRAPHICS PM graphics are enabled by the direct memory access control register, DMACTL [$D400 (54272)]. The program using PM graphics will usually use the shadow register, SDMCTL [$022F (559)]. DMACTL (SDMCTL) 7 6 5 4 3 2 1 0 ----------------- |0|0| control | ----------------- bits 5 1 = enable display list reading 4 0 = one line player resolution 1 = two line player resolution 3 1 = enable four players 2 1 = enable fifth player or missiles 1 & 0 00 = no background 01 = narrow background (128 color clocks, 1 color clock equals 2 GRAPHICS 8 pixels) 10 = normal background (160 color clocks) 11 = wide background (192 color clocks) Normally, bits 5 and 1 are set to 1. Bits 4, 3 and 2 are used to enable players and/or missiles accordingly. Once DMACTL is set up for the type of PM graphics to enable, the graphics control register, GRACTL [$D01D (53277)], is used to actually enable the PM graphics. GRACTL 7 6 5 4 3 2 1 0 ----------------- |not used | | | | ----------------- Bits 2 1 = latch paddle triggers 1 1 = enable four players 0 1 = enable fifth player or missiles If only DMACTL is set up, the ANTIC chip will access memory for PM graphics but will not display them. Next, the memory area used for the PM bit maps must be set. This block must start on a 2K (8 page) boundary if single line resolution is used and a 1K (4 page) boundary for two line resolution. The page number where the bit map starts is stored in the PM base register, PMBASE [$D407 (54279)]. For one line resolution this number will be a multiple of 8. For two line resolution it will be a multiple of 4. PMBASE holds the MSB of the address of the PM bit map. The LSB will always be 0 so it need not be specified. The PM bit maps 2 line resolution 128 bytes (1/2 page) per player ----------------- start + 0 | |\ +---------------+ 1-1/2 page | | (384 bytes) +===============+ unused | |/ +---------------+ +$180 (384) |M3 |M2 |M1 |M0 | fifth player or missiles +===============+ +$200 (512) | player 0 map | +---------------+ +$280 (640) | player 1 map | +===============+ +$300 (768) | player 2 map | +---------------+ +$380 (896) | player 3 map | +===============+ +$400 (1024) 1 line resolution 256 bytes (1 page) per player ----------------- start + 0 | |\ + + | | +===============+ | | 768 bytes + + | | (3 pages) +===============| | | unused + + | |/ +===============+ +$300 (768) | | | | | fifth player +M3 |M2 |M1 |M0 | or missiles | | | | | +===============+ +$400 (1024) | | + player 0 map + | | +===============+ +$500 (1280) | | + player 1 map + | | +===============+ +$600 (1536) | | + player 2 map + | | +===============+ +$700 (1792) | | + player 3 map + | | +===============+ +$800 (2048) Example of using P/M graphics in BASIC 0 REM ---LABEL REGISTERS ETC 10 LINES=2 20 VERT=120 22 IF LINES=2 THEN VERT=VERT/2 30 PM0=1024 32 IF LINES=2 THEN PM0=PM0/2 40 HORIZ=120 50 PCOLR0=704 60 SDMCTL=559 70 SIZEP0=53256 80 HPOSP0=53248 90 SDMCTL=559 100 PMRAM=PEEK(106)-16 110 PMBASE=54279 120 GRACTL=53277 130 PMSTART=PMRAM*256+PM0 200 REM ---SET REGISTERS 210 POKE SDMCTL,62 212 IF LINES=2 THEN POKE SDMCTL,46 220 POKE SIZEP0,1 230 POKE HPOSP0,HORIZ 240 POKE PCOLR0,88 250 POKE PMBASE,PMRAM 260 POKE GRACTL,3 300 REM ---DRAW PLAYER 310 POKE PMSTART+VERT,60 320 POKE PMSTART+VERT+1,66 330 POKE PMSTART+VERT+2,165 340 POKE PMSTART+VERT+3,129 350 POKE PMSTART+VERT+4,195 360 POKE PMSTART+VERT+5,189 370 POKE PMSTART+VERT+6,66 380 POKE PMSTART+VERT+7,60 The above program will draw a happy face in about the middle of the screen using player 0. To move the player horizontally, poke a different number into HPOSP0. To draw the player in a different vertical position, change VERT. To use a different player or missile, use the memory maps above to find the starting address of the player you want to use. For example, to use player 1 change line 40 to PM1=1280. Then change line 130 to PMSTART=PMRAM*256+PM1. The variable "LINES" determines the vertical resolution. The number poked into SIZEP0 determines the width. P/M PRIORITY The priorities of players, missiles and non-P/M graphics can be controlled by the PRIOR register [$D10B (53275)] and its shadow register, GPRIOR [$26F (623)]. Objects with higher priority will appear to move in front of lower priority objects. The format of PRIOR is as follows: PRIOR bit assignment 7 6 5 4 3 2 1 0 ----------------- | | | | | | | | | ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 Bits 7-6 Control the GTIA graphics modes. 00 = normal 01 = mode 9 10 = mode 10 11 = mode 11 5 1 = multiple color player enable. Permits overlapping of players 0 and 1 or 2 and 3 with a third color in the overlapped region. 4 1 = fifth player enable. All missiles will assume the color controlled by COLOR3 [$2C7 (711)]. missiles are positioned together to make the fifth player. 3-0 Controls the priorities of players, missiles and other graphics. Objects with higher priority will appear to move in front of those with lower priority. The following chart may need some clarification. In the chart: PM0 = player 0 and missile 0 C0 = COLOR0, plotted graphics controlled by color register 0 in the SETCOLOR command. P5 = all four missiles when combined into one player. BAK = the background, known as COLOR4 or color register 4 in the SETCOLOR command. Etc. Bits 0-3 of PRIOR and P/M priorities Bit 3=1 2=1 1=1 0=1 C0 C0 PM0 PM0 highest C1 C1 PM1 PM1 priority PM0 C2 C0 PM2 PM1 C3+P5 C1 PM3 PM2 PM0 C2 C0 PM3 PM1 C3+P5 C1 C2 PM2 PM2 C2 C3+P5 PM3 PM3 C3+P5 lowest BAK BAK BAK BAK priority Only one priority bit can be set at a time. If more than one priority bit is 1, overlapping areas of conflicting priorities will turn black. COLLISIONS Each player or missile has a register showing overlap (collisions) with other objects. Each player has two registers assigned to it; one to detect collisions with other players and one to detect collisions with plotted objects. Likewise each missile has two registers; one to detect collisions with players and one to detect collisions with plotted objects. Careful use of these 16 registers can detect any type of collision. Each register uses only the lower 4 bits. The bits which equal 1 tell what the associated object has collided with. For example, to detect collisions of player 1 to other players examine P1PL [$D00D (53261)]. P1PL, player 1 to player collisions 7 6 5 4 3 2 1 0 ----------------- P1PL |unused | | | | | ----------------- 8 4 2 1 3 = 1 collision with player 3 2 = 1 collision with player 2 1 = 1 invalid 0 = 1 collision with player 0 Etc. When looking for collisions with plotted objects, the bit number tells what color register is assigned to the object the collision was with. For example, to detect collisions between player 1 and plotted objects (officially called the play field), P1PF [$D005 (53253)] is used. P1PF, player 1 to ploted object collisions 7 6 5 4 3 2 1 0 ----------------- P1PF |unused | | | | | ----------------- 8 4 2 1 3 = 1 collision with COLOR3 2 = 1 " COLOR2 1 = 1 " COLOR1 0 = 1 " COLOR0 Etc. Once a collision occurs it remains indicated in its collision register. To clear out all collision registers, write anything to HITCLR [$D01E (53278)]. STA HITCLR or POKE 53278,0 will do. Useful database variables and OS equates HPOSP0 $D000 (53248): write: horizontal position of player 0 M0PF " " : read: missile 0 to plotted graphics collisions HPOSP1 $D001 (53249): write: horizontal position of player 1 M1PF " " : read: missile 1 to plotted graphics collisions HPOSP2 $D002 (53250): write: horizontal position of player 2 M2PF " " : read: missile 2 to plotted graphics collisions HPOSP3 $D003 (53251): write: horizontal position of player 3 M3PF " " : read: missile 3 to plotted graphics collisions HPOSM0 $D004 (53252): write: horizontal position of missile 0 P0PF " " : read: Player 0 to plotted graphics collisions HPOSM1 $D005 (53253): write: horizontal position of missile 1 P1PF " " : read: Player 1 to plotted graphics collisions HPOSM2 $D006 (53254): write: horizontal position of missile 2 P2PF " " : read: Player 2 to plotted graphics collisions HPOSM3 $D007 (53255): write: horizontal position of missile 3 P3PF " " : read: Player 3 to plotted graphics collisions SIZEP0 $D008 (53256): write: size of player 0 M0PL " " : read: missile 0 to player collisions SIZEP1 $D009 (53257): write: size of player 1 M1PL " " : read: missile 1 to player collisions SIZEP2 $D00A (53258): write: size of player 2 M2PL " " : read: missile 2 to player collisions SIZEP3 $D00B (53259): write: size of player 3 M3PL " " : read: missile 3 to player collisions SIZEM $D00C (53260): write: widths for all missiles P0PL " " : read: player 0 to other player collisions GRAFP0 $D00D (53261): write: player 0 graphics (used by OS) P1PL " " : read: player 1 to other player collisions GRAPF1 $D00E (53262): write: player 1 graphics P2PL " " : read: player 2 to other player collisions GRAFP2 $D00F (53263): write: player 2 graphics P3PL " " : read: player 3 to other player collisions GRAPF3 $D010 (53264): write: player 3 graphics GRAFM $D011 (53265): write: missile graphics (used by OS) COLPM0 $D012 (53266): color for player/missile 0 COLPM1 $D013 (53267): color for player/missile 1 COLPM2 $D014 (53268): color for player/missile 2 COLPM3 $D015 (53269): color for player/missile 3 COLPF0 $D016 (53270): color register 0 COLPF1 $D017 (53271): color register 1 COLPF2 $D018 (53272): color register 2 COLPF3 $D019 (53273): color register 3 COLBK $D01A (53274): background color (register 4) PRIOR $D01B (53275): priority select, GTIA modes GRACTL $D01D (53277): graphics control HITCLR $D01E (53278): writing anything clears all collision bits DMACTL $D400 (54272): direct memory access (DMA) control PMBASE $D407 (54279): start of P/M memory Shadow registers SDMCTL $022F (559): DMACTL GPRIOR $026F (623): PRIOR PCOLR0 $02C0 (704): COLPM0 PCOLR1 $02C1 (705): COLPM1 PCOLR2 $02C2 (706): COLPM2 PCOLR3 $02C3 (707): COLPM3 COLOR0 $02C4 (708): COLPF0 COLOR1 $02C5 (709): COLPF1 COLOR2 $02C6 (710): COLPF2 COLOR3 $02C7 (711): COLPF3 COLOR4 $02C8 (712): COLBK CHAPTER 17 SOUND Generating sound can be very simple. For simple sounds there are four audio channels, each controlled by two control registers. GENERATING SOUNDS To generate a sound in channel 1, put the frequency and volume codes into the frequency and control registers. The frequency register for channel 1, AUDF1 [$D200 (53760)] can have any number from 0 to $FF (255). 0 causes the highest frequency; 255 causes the lowest. The volume/noise (control) register for channel 1, AUDC1 [$D201 (53761)] is more complicated. Audio channel control (volume/noise) register 7 6 5 4 3 2 1 0 ----------------- AUDCx | noise | volume| ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 The noise bits can have various values. The best way to learn to use them is by experimentation. The technical details of the polynomial counters which generate the noise has little bearing on what is heard. The two special values of interest are: $1 (volume+16 in decimal), which causes a DC voltage proportional to the volume bits and; $A (volume+160), which causes a pure tone (square wave). The volume bits select the relative volume, 0=off. Therefore, the number, $A8 (168 [8+160]) in AUDC1, will cause the frequency selected by AUDF1 to be a pure tone of medium volume. In BASIC the dirty work is done fore you. The SOUND command will do all the calculations for you. The Sound command format is shown below. The BASIC sound command format SOUND channel,frequency,noise,volume The channel numbers is 0 to 3 instead of 1 to 4. The frequency, 0 to 255, is put into the frequency register. The noise is put into the high bits of the channel control register with volume in the low bits. Therefore... SOUND 0,125,10,8 will produce a pure tone of medium frequency and volume in channel 0 (called channel 1 in assembly language). ADVANCED SOUND The Audio Control register, AUDCTL [$D208 (53768)], (not to be confused with the four audio channel control registers), adds more control for assembly language programmers. Again, to go into technical details will be less productive than experimentation. The audio control register. (AUDCTL) 7 6 5 4 3 2 1 0 ----------------- AUDCTL | | | | | | | | | ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 7 0 = 17 bit polynomial noise 1 = 9 bit below polynomial noise 6 0 = clock channel 1 with 64 KHz 1 = clock channel 1 with 1.79 MHz 5 0 = clock channel 3 with 64 KHz 1 = clock channel 3 with 1.79 MHz 4 0 = clock channel 2 with 64 KHz 1 = clock channel 2 with channel 1 3 0 = clock channel 4 with 64 KHz 1 = clock channel 4 with channel 3 2 1 = insert logical high-pass filter in channel 1, clocked by channel 3 1 1 = insert logical high-pass filter in channel 2, clocked by channel 4 0 0 = 64 KHz main clock 1 = 16 KHz main clock All bits of AUDCTL are normally zero. The BASIC sound command causes it to be reset to zero. By clocking one channel with another, the range can be increased. This essentially allows two channels with twice the range as each of the four normal channels. This is called 16 bit sound. To calculate exact frequencies, use the following formulas. The exact clock frequencies are also given if more accuracy is needed. The clock frequencies are acquired by dividing the signal from the TV color-burst crystal. This crystal has a frequency of 3.579545 MHz. Clock frequencies: 1.7897725 MHz (color-burst/2) 63.920446 Khz (color-burst/56) 15.699759 KHz (color-burst/228) Formulas: For 1.79 MHz clock clock f = ------------ f = ------------ 2(AUDFn + 7) 2(AUDFn + 4) 16 bit 8 bit AUDFn is the number in the audio frequency register. For 16 KHz and 64 KHz clock f = ------------ 2(AUDFn + 1) AUDIO TIMER INTERRUPTS When the audio timers count down to zero they generate IRQ interrupts (if enabled). The timers can be reset by writing any number to STIMER [D209 (53769)]. THE CONSOLE SPEAKER The console speaker is where key clicks and the cassette signals come from. On XL and XE models this speaker is heard through the TV speaker. It is operated by toggling bit 3 of CONSOL [$D01F (53279). This bit always reads 0 but it is actually set to 1 during vertical blank. Useful data base variables and OS equates CONSOL $D01F (53279): bit 3 controls console speaker AUDF1 $D200 (53760): Audio frequency 1 AUDC1 $D201 (53761): audio control 1 AUDF2 $D202 (53762): Audio frequency 2 AUDC2 $D203 (53763): audio control 2 AUDF3 $D204 (53764): Audio frequency 3 AUDC3 $D205 (53765): audio control 3 AUDF4 $D206 (53766): Audio frequency 4 AUDC4 $D207 (53767): audio control 4 AUDCTL $D208 (53768): general audio control STIMER $D209 (53769): audio timer reset CHAPTER 18 THE JOYSTICK PORTS The joystick ports are the I/O ports of the PIA chip. This means that they are bidirectional, capable of output as well as input. The joystick ports are usually set up for input. To read them, simply read the port registers. PORTA [$D300 (53016)] will read joystick ports 1 and 2. PORTB [$D301 (54017)] will read joystick ports 3 and 4. Joystick ports 3 and 4 are used for memory control on the XL/XE models and don't have external connectors. Each bit of each port can be configured independently for input or output. To reconfigure a port, the port control registers, PACTL and PBCTL [$D302 (54018) and $D303 (54019)], are used. The port control registers also control some lines on the serial I/O connector. The port control registers 7 6 5 4 3 2 1 0 PACTL ----------------- or |n 0 1 1 n n 0 n| PBCTL ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 bits PACTL 7 Peripheral A interrupt status. Set by peripheral interrupt; reset by reading PORTA. 3 Cassette motor control (0 = on: 1 = off). 2 0 = PORTA is now port A direction control. Writing to PORTA will now set bits for input or output. 0 sets bit for input; 1 sets bit for output. 1 = PORTA operational 1 1 = peripheral A interrupt enabled. PBCTL 7 Peripheral B interrupt status. Set by peripheral interrupt; reset by reading PORTB. 3 Serial connector command line. 2 0 = PORTB is now port B direction control. Writing to PORTB will now set bits for input or output. 0 sets bit for input; 1 sets bit for output. 1 = PORTB operational 1 1 = peripheral B interrupt enabled. The electronic configuration of the controller ports is as follows. ----------- ----------- \0 1 2 3 R/ \4 5 6 7 R/ \t + - L/ \t + - L/ ------- ------- 0 through 7 are the binary data bits for port A or port B. + and - are +5 volts and ground respectively. R and L are the left and right game paddles. t is the joystick trigger line. The data bits in the joystick ports are used as follows for the joysticks and game paddles. The joysticks and the port registers 7 6 5 4 3 2 1 0 ----------------- PORTA |U|D|L|R|U|D|L|R| ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 paddle | | | | triggers 3 2 1 0 PORTB ----------------- (400/800 |U|D|L|R|U|D|L|R| only) ----------------- paddle | | | | triggers 7 6 5 4 U = up D = down L = left R = right The joysticks may be read either directly from the port registers or from the joystick shadow registers. During vertical blank, the data in the port registers is separated and put into the shadow registers. These registers are, STICK0 [$0278 (632)], STICK1 [$0279 (633)], STICK2 [$027A (634)] and STICK3 [$027B (635)]. The triggers may be read from the joystick trigger registers, TRIG0 - TRIG3 [$D010 - $D013 (53264 - 53267)]. These register have shadow registers, STRIG0 - STRIG3 [$0284 - 0287 (644 -647)]. If these registers read zero the associated triggers are pressed. The paddle triggers may be read from their shadow registers also. They are, PTRIG0 - PTRIG 7, [$027C - $0283 (236 - 643)]. THE GAME PADDLE REGISTERS Although the game paddles are plugged into the joystick ports, they are not read from the port registers. The game paddles are read by first writing any number to the start-pot-scan register, POTGO [$D20B (53771)]]. This turns off the capacitor dump transistors and allows the pot reading capacitors to begin charging. It also sets the TV scan line counter to zero. As each capacitor crosses a certain trigger voltage, the number of TV lines scanned is put in the respective pot value register. When the scan counter reaches 228, the capacitor dump transistors are turned on and the number 228 is put into any pot value registers which are still empty. Before reading the pot value registers, ALLPOT [$D208 (53768)] should be checked. In this register, each bit corresponds to the validity of a pot value register. If a bit is zero, its' associated pot value register is valid. If bit 2 of SKCTL, [$D20F (53775)], is 1, the pots go into the fast scan mode. In this mode the paddles are read in only 2 TV scan lines. They can also be read without regard to POTGO or ALLPOT. The pot value registers contain the number of TV scan lines it last took for the paddle reading capacitors to charge (up to 228). These registers are POT0 - POT7 [$D200 - $D207 (53760 -53767)]. Their shadow registers are PADDL0 - PADDL7 [$0270 - $0277 (624 - 631)]. THE LIGHT PEN REGISTERS Whenever a joystick trigger is pressed, the light pen registers, PENH and PENV are updated. PENH [$D40C (54284)] takes a value based on a color clock counter. The value can be from 0 to 227. PENV [$D40D [54285)] takes the 8 highest bits of the vertical line counter. A light pen is simply a photo transistor connected to a joystick trigger line and focused on the TV screen. When the electron beam strikes the part of the screen the light pen is focused on, the transistor turns on pulling the trigger line low. The light pen registers then contain numbers relative to where the light pen was pointing. The shadow register for PENH and PENV are LPENH [$0234 (564)] and LPENV [$0235 (566)). Useful operating system equates TRIG0 $D010 (53264): joystick triggers | TRIG3 $D013 (53268): POT0 $D200 (53760): paddle value | POT7 $D207 (53767): ALLPOT $D208 (53768): reads validity of pot values POTGO $D20B (53771): starts paddle read SKCTL $D20F (53775): bit 2 enables fast pot scan PORTA $D300 (53016): port A data PORTB $D301 (53017): port B data PACTL $D302 (54018): port A control PBCTL $D303 (54019): port B control PENH $D40C (54284): light pen horizontal value PENV $D40D (54285): light pen vertical value Shadow registers LPENH $0234 (564): light pen horizontal value LPENV $0235 (566): light pen vertical value PADDL0 $0270 (624): game paddle values | PADDL7 $0277 (631) STICK0 $0278 (632): joystick registers | STICK0 $027B (635): PRTIG0 $027C (636): paddle triggers | PTRIG7 $0283 (643): STRIG0 $0284 (644): joystick triggers | STRIG3 $0287 (647): CHAPTER 19 MISC HARDWARE REGISTERS AND INFORMATION VERTICAL LINE COUNTER The ANTIC chip has a vertical line counter at $0D4B (54283). This counter shows the high 8 bits of a 9 bit counter. This gives two line resolution. The value of this counter is placed into PENV [$D40D (54285)] when a joystick trigger is pressed. SERIAL PORT REGISTERS The POKEY chip has some registers which control the serial port. The serial port control register, SKCTL [$D20F (53775)], controls the serial port configuration and the game paddle scan mode. and some keyboard circuitry. The serial port control register 7 6 5 4 3 2 1 0 ----------------- SKCTL | | | | | | | | | ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 bits 0 1 = enable keyboard debounce 1 1 = enable keyboard scan both 0 = set initialization mode. 2 1 = fast pot scan 3 1 = serial output is two tone (for cassette) instead of logical true/false 4\ 5 >- serial port mode control 6/ 7 1 = forced logical 0 on output If the serial port control register is read from it gives the serial port status. The register is then called SKSTAT Serial port status register 7 6 5 4 3 2 1 0 ----------------- | | | | | | | |1| ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 bits 0 not used, reads 1 1 0 = serial input shift register busy 2 0 = last key is still pressed 3 0 = shift key pressed 4 0 = direct from serial input port 5 0 = keyboard over-run 6 0 = serial data input over-run 7 1 = serial data input frame error The serial port status is latched and must be reset by writing any number to its' reset register, SKRES [$D20A (53770)]. SERIAL PORT INPUT AND OUTPUT DATA When a full byte of serial input data has been received, it is read from the serial input data register, SERIN [$D20D (53773). Serial output data is written to the same register, which is then called the serial output data register, SEROUT. This register is usually written to in response to a serial output data interrupt (bit 4 of IRQST). HARDWARE CHIP MEMORY ALLOCATION The addresses for the hardware chips are not completely decoded. For example, the PIA needs only four bytes of memory but is active from $D300 - D3FF. Enough room for 64 PIA chips. A second pair of parallel ports could be added by accessing the address bus and further decoding the address for a second PIA. (This would also require a small modification of the computer's circuit board to disable the original PIA when the new one is active.) Similarly, there is room for 15 more POKEY or ANTIC chips and 7 gtia chips, should you ever need them. (GTIA uses $D000 - D0FF, POKEY uses $D200 - $D2FF and ANTIC uses $D400 - $D4FF.) Useful data base variables and OS equates SKRES $D20A (53770): serial port status reset SEROUT $D20D (53773): serial output data SERIN $D20D (53773): serial input data SKCTL $D20F (53775): serial port control SKSTAT $D20F (53775): serial port status VCOUNT $D40B (54283): vertical line counter Os shadow registers SSKCTL $0232 (562): SKCTL CHAPTER 20 THE XL AND XE MODELS BASIC B BUGS Most of the Atari 600XL and 800XL models were supplied with the "debugged" version B of Atari BASIC. This new BASIC got rid of the minor bugs of BASIC A and introduced some new major bugs of it's own. Each time a program is saved, 16 extra bytes are tagged onto the end of the program. After many saves and reloads, as when developing a long program, the program becomes too large for the memory. The computer may lock up unpredictably. Program line links may get messed up, leaving garbage in the listing and the program unrunable. Large LISTed programs may not run unless SAVed and reLOADed. If the length of a listed program is a multiple of a certain number of bytes, it will not run unless the length is somehow changed. BASIC version B has been replaced by version C. All of the XE models have this truly debugged version of BASIC. NEW OPERATING SYSTEM PROBLEMS I have heard of only one bug in the operating system in XL and XE models. This is a mishandling of the printer timeout. The computer cannot tell if there is a printer attached or not. This may have been fixed in the XE models. However, many programs, some even formerly sold by Atari, do not jump through published jump vectors when using the operating system. These programs will not run on XL/XE models. (Some of these programs are Atari Word Processor (not Atariwriter) and LJKs Letter Perfect and Data Perfect.) Since the operating system ROM can be switched to RAM, a "translator" can be used to load the 800 operating system into an XL or XE model. 130XE MEMORY MANAGEMENT The 130XE has an extra 64K bank of memory. It is divided into four blocks of 16K each. Each block can be switched to replace part of the main bank of RAM from $4000 (16384) to $7FFF (32767). Furthermore, it can be switched in such a way that only the 6502, or the ANTIC chip can see the extra memory. Port B (formerly the two extra joystick ports of the 400/800) is used to manage the memory. Port B and memory management 7 6 5 4 3 2 1 0 ----------------- PORTB |T|U|A|C|S S|B|R| ----------------- 1 6 3 1 8 4 2 1 2 4 2 6 8 R 1 = OS replaced by RAM B 0 = BASIC enabled S S bank select bits C 0 = CPU sees switched RAM at $4000 A 0 = ANTIC sees switched RAM U unused T 0 = self test Bits 2 and 3 of PORTB select which block of the extra bank of memory is switched in. Bank select bits bits block 2 3 address ------------------------- 0 0 $0000 - $3FFF 0 1 $4000 - $7FFF 1 0 $8000 - $BFFF 1 1 $C000 - $FFFF Bits 4 and 5 select which chip sees the switched in RAM at $4000 - $7FFF Chip select bits bits ANTIC 6502 4 5 -------------------------- 0 0 Ext. Ext. 0 1 Ext. Main 1 0 Main Ext. 1 1 Main Main THE XL PARALLEL PORT Pin out of the parallel port top from rear 111112222233333444445 2468024680246802468024680 ------------------------- ------------------------- 11111222223333344444 1357913579135791357913579 1 2 GND 3 A1 4 A0 5 A3 6 A2 7 A5 8 A4 9 GND 10 A6 11 A8 12 A7 13 A10 14 A9 15 A12 16 A11 17 A14 18 A13 19 A15 20 GND 21 D1 22 D0 23 D3 24 D2 25 D5 26 D4 27 D7 28 D6 29 GND 30 GND 31 GND 32 phase 2 clock 33 RESET 34 35 RDY 36 IRQ 37 37 39 40 41 GND 42 43 RAS 44 45 R/W 46 GND 47 +5V 48 +5V 49 GND 50 The phase 2 clock runs at 1.8 MHz. When the clock is high, the address and R/W lines are valid. The clock goes from high to low, when the data lines are also valid. All lines then become invalid. The 130XE doesn't have the parallel port. However, it has a cartridge slot expansion. This is a small cartridge-slot-like connector with the necessary connector to use parallel expansion. FINE SCROLLING If address $026E (622) is $FF, graphics 0 will be in the fine scroll mode. OTHER ADDRESSES DSCTLN [$0D25,2 (725)] is the disk sector size. should be $80 (128). DMASAV [$02DD (735)] is a copy of the DMA control register, SDMCTL [$022F (559)]. It is set up when a channel is opened to the screen. The value is moved to SDMCTL whenever a key is pressed. It is used to restore the display if DMA is disabled. PUPBT [$033D,3 (829-831)] is used to test memory integrity when [RESET] is pressed. If these bytes are not $5C, $93 and $25, the computer will do a cold start when [RESET] is pressed. The self-test ROM is from $D000 to $D7FF, the same addresses as the hardware registers. This part of the operating system ROM is disabled when not used. When The computer is put into the self-test mode, This part of ROM is copied to $5000 to $57FF and run from there. GINTLK [$03FA (1018)] is a logical 1 if a cartridge is installed (built-in BASIC is considered a cartridge). BASIC can be disabled by poking 1018 with a non-zero number. If [RESET] is then pressed, the computer will attempt to load the DUP.SYS file and basic will be completely disabled. APPENDIX A HARDWARE REGISTERS Register Shadow Name Description Address Name Address ---------------------------------------------------------------------- ALLPOT game paddle ready indicators $D208 53768 AUDC1 Audio channel 1 control $D201 53761 AUDC2 Audio channel 2 control $D203 53763 AUDC3 Audio channel 3 control $D205 53765 AUDC4 Audio channel 1 control $D207 53767 AUDCTL general audio control $D208 53768 AUDF1 Audio frequency 1 control $D200 53760 AUDF2 Audio frequency 2 control $D202 53762 AUDF3 Audio frequency 3 control $D204 53764 AUDF4 Audio frequency 4 control $D206 53766 CHACTL character control $D401 54273 CHART $02F3 755 CHBASE Address of character set / 256 $D409 54281 CHBAS $O2F4 756 COLBK color/brightness of setcolor 4 $D01A 53274 COLOR4 $02C8 712 COLPF0 Color/brightness of setcolor 0 $D016 53270 COLOR0 $02C4 708 COLPF1 color/brightness of setcolor 1 $D017 53271 COLOR1 $02C5 709 COLPF2 color/brightness of setcolor 2 $DO18 53272 COLOR2 $02C6 710 COLPF3 color/brightness of setcolor 3 $DO19 53273 COLOR3 $02C7 711 COLPM0 color/brightness, player/missile 0 $D012 53266 PCOLR0 $02C0 704 COLPM1 color/brightness, player/missile 1 $DO13 53267 PCOLR1 $02C1 705 COLPM2 color/brightness, player/missile 2 $DO14 53268 PCOLR2 $02C2 706 COLPM3 color/brightness, player/missile 3 $DO15 53269 PCOLR3 $02C3 707 CONSOL [START], [SELECT], [OPT.], speaker $D01F 53279 DLISTH display list pointer high byte $D403 54275 SDLSTH $0231 561 DLISTL display list pointer low byte $D402 54274 SDLSTL $0230 560 DMACTL Direct Memory access control (DMA) $D400 54272 SDMCTL $022F 559 GRACTL graphics control $D01D 53277 GRAFM missile graphics $D011 53265 GRAFP0 player 0 graphics $D00D 53261 GRAFP1 player 1 graphics $D00E 53262 GRAFP2 player 2 graphics $D00F 53263 GRAFP3 player 3 graphics $D010 53264 HITCLR clear collisions $D01E 54278 HPOSM0 horizontal position of missile 0 $D004 53252 HPOSM1 horizontal position of missile 1 $D005 53253 HPOSM2 horizontal position of missile 2 $D006 53254 HOPSM3 horizontal position of missile 3 $D007 53255 HPOSP0 horizontal position of player 0 $D000 53248 HPOSP1 horizontal position of player 1 $D001 53249 HPOSP2 horizontal position of player 2 $D002 53250 HPOSP3 horizontal position of player 3 $D003 53251 HSCROL horizontal scroll $D404 54276 IRQEN interrupt request enable (IRQ) $D20E 53774 POKMSK $0010 16 IRQST IRQ status $D20E 53774 KBCODE keyboard code $D209 53769 CH $O2FC 764 M0PF missile 0 to graphics collisions $D000 53248 M0PL missile 0 to player collisions $D008 53256 M1PF missile 1 to graphics collisions $D001 53249 M1PL missile 1 to player collisions $D009 53257 M2PF missile 2 to graphics collisions $D002 53250 M2PL missile 2 to player collisions $D00A 53258 M3PF missile 3 to graphics collisions $D003 53251 M3PL missile 3 to player collisions $D00B 53259 NMIEN non-maskable interrupt enable (NMI)$D40E 54286 NMIRES NMI reset $D40F 54287 NMIST NMI status $D40F 54287 P0PF player 0 to graphics collisions $D004 53252 P0PL player 0 to player collisions $D00C 53260 P1PF player 1 to graphics collisions $D005 53253 P1PL player 1 to player collisions $D00D 53261 P2PF player 2 to graphics collisions $D006 53254 P2PL player 2 to player collisions $D00E 53262 P3PF player 3 to graphics collisions $DOO7 53255 P3PL player 3 to player collisions $D00F 53263 PACTL port A control $D302 54018 PAL Europe/North America TV indicator $D014 53268 PBCLT port B control $D303 54019 PENH light pen horizontal position $D40C 54284 LPENH $0234 564 PENV light pen vertical position $D40D 54285 LPENV $0235 565 PMBASE player/missile address / 256 $D407 54279 PORTA port A $D300 54016 STICK0 $0278 632 STICK1 $0279 634 PORTB port B $D301 54017 STICK2 $027A 634 STICK3 $027B 635 POT0 game paddle 0 $D200 53760 PADDL0 $0270 624 POT1 game paddle 1 $D201 53761 PADDL1 $0271 625 POT2 game paddle 2 $D202 53762 PADDL2 $0272 626 POT3 game paddle 3 $D203 53763 PADDL3 $0273 627 POT4 game paddle 4 $D204 53764 PADDL4 $0274 628 POT5 game paddle 5 $D205 53765 PADDL5 $0275 629 POT6 game paddle 6 $D206 53766 PADDL6 $0276 630 POT7 game paddle 7 $D207 53767 PADDL7 $0277 631 POTGO start pot scan sequence $D20B 53771 PRIOR p/m priority and GTIA mode $D21B 53275 GPRIOR $026F 623 RANDOM random number generator $D20A 53770 SERIN serial port input $D20D 53774 SEROUT serial port output $D20D 53773 SIZEM missile size $D00C 53260 SIZEP0 player 0 size $D008 53256 SIZEP1 player 1 size $D009 53257 SIZEP2 player 2 size $D00A 53258 SIZEP3 player 3 size $D00B 53259 SKCTL serial port control $D20F 53775 SSKCTL $0232 563 SKREST reset serial port status $D20A 53770 SKSTAT serial port status $D20F 53775 STIMER start timer $D209 53769 TRIG0 joystick trigger 0 $D010 53264 STRIG0 $0284 644 TRIG1 joystick trigger 1 $D011 53265 STRIG1 $0285 645 TRIG2 joystick trigger 2 $D012 53266 STRIG2 $0286 646 TRIG3 joystick trigger 3 $D013 53267 STRIG3 $0287 647 VCOUNT vertical line counter $D40B 54283 VDELAY vertical delay $D01C 54276 VSCROL vertical scroll $D405 54277 WSYNC wait for horizontal sync $D40A 54282 NUMERICAL ORDER Registers sharing addresses are listed first when writen to, then when read from Register Shadow Name Description Address Name Address ---------------------------------------------------------------------- HPOSP0 horizontal position of player 0 $D000 53248 M0PF missile 0 to graphics collisions $D000 53248 HPOSP1 horizontal position of player 1 $D001 53249 M1PF missile 1 to graphics collisions $D001 53249 HPOSP2 horizontal position of player 2 $D002 53250 M2PF missile 2 to graphics collisions $D002 53250 HPOSP3 horizontal position of player 3 $D003 53251 M3PF missile 3 to graphics collisions $D003 53251 HPOSM0 horizontal position of missile 0 $D004 53252 P0PF player 0 to graphics collisions $D004 53252 HPOSM1 horizontal position of missile 1 $D005 53253 P1PF player 1 to graphics collisions $D005 53253 HPOSM2 horizontal position of missile 2 $D006 53254 P2PF player 2 to graphics collisions $D006 53254 HOPSM3 horizontal position of missile 3 $D007 53255 P3PF player 3 to graphics collisions $D007 53255 SIZEP0 player 0 size $D008 53256 M0PL missile 0 to player collisions $D008 53256 SIZEP1 player 1 size $D009 53257 M1PL missile 1 to player collisions $D009 53257 SIZEP2 player 2 size $D00A 53258 M2PL missile 2 to player collisions $D00A 53258 SIZEP3 player 3 size $D00B 53259 M3PL missile 3 to player collisions $D00B 53259 SIZEM missile size $D00C 53260 P0PL player 0 to player collisions $D00C 53260 GRAFP0 player 0 graphics $D00D 53261 P1PL player 1 to player collisions $D00D 53261 GRAFP1 player 1 graphics $D00E 53262 P2PL player 2 to player collisions $D00E 53262 GRAFP2 player 2 graphics $D00F 53263 P3PL player 3 to player collisions $D00F 53263 GRAFP3 player 3 graphics $D010 53264 TRIG0 joystick trigger 0 $D010 53264 STRIG0 $0284 644 GRAFM missile graphics $D011 53265 TRIG1 joystick trigger 1 $D011 53265 STRIG1 $0285 645 COLPM0 color/brightness, player/missile 0 $D012 53266 PCOLR0 $02C0 704 TRIG2 joystick trigger 2 $D012 53266 STRIG2 $0286 646 COLPM1 color/brightness, player/missile 1 $D013 53267 PCOLR1 $02C1 705 TRIG3 joystick trigger 3 $D013 53267 STRIG3 $0287 647 COLPM2 color/brightness, player/missile 2 $D014 53268 PCOLR2 $02C2 706 PAL Europe/North America TV indicator $D014 53268 COLPM3 color/brightness, player/missile 3 $D015 53269 PCOLR3 $02C3 707 COLPF0 Color/brightness of setcolor 0 $D016 53270 COLOR0 $02C4 708 COLPF1 color/brightness of setcolor 1 $D017 53271 COLOR1 $02C5 709 COLPF2 color/brightness of setcolor 2 $D018 53272 COLOR2 $02C6 710 COLPF3 color/brightness of setcolor 3 $D019 53273 COLOR3 $02C7 711 COLBK color/brightness of setcolor 4 $D01A 53274 COLOR4 $02C8 712 VDELAY vertical delay $D01C 54276 GRACTL graphics control $D01D 53277 HITCLR clear collisions $D01E 54278 CONSOL [START], [SELECT], [OPT.], speaker $D01F 53279 AUDF1 Audio frequency 1 control $D200 53760 POT0 game paddle 0 $D200 53760 PADDL0 $0270 624 AUDC1 Audio channel 1 control $D201 53761 POT1 game paddle 1 $D201 53761 PADDL1 $0271 625 AUDF2 Audio frequency 2 control $D202 53762 POT2 game paddle 2 $D202 53762 PADDL2 $0272 626 AUDC2 Audio channel 2 control $D203 53763 POT3 game paddle 3 $D203 53763 PADDL3 $0273 627 AUDF3 Audio frequency 3 control $D204 53764 POT4 game paddle 4 $D204 53764 PADDL4 $0274 628 AUDC3 Audio channel 3 control $D205 53765 POT5 game paddle 5 $D205 53765 PADDL5 $0275 629 AUDF4 Audio frequency 4 control $D206 53766 POT6 game paddle 6 $D206 53766 PADDL6 $0276 630 AUDC4 Audio channel 1 control $D207 53767 POT7 game paddle 7 $D207 53767 PADDL7 $0277 631 ALLPOT game paddle ready indicators $D208 53768 AUDCTL general audio control $D208 53768 KBCODE keyboard code $D209 53769 CH $O2FC 764 STIMER start timer $D209 53769 RANDOM random number generator $D20A 53770 SKREST reset serial port status $D20A 53770 POTGO start pot scan sequence $D20B 53771 SEROUT serial port output $D20D 53773 SERIN serial port input $D20D 53774 IRQEN interrupt request enable (IRQ) $D20E 53774 POKMSK $0010 16 IRQST IRQ status $D20E 53774 SKCTL serial port control $D20F 53775 SSKCTL $0232 563 SKSTAT serial port status $D20F 53775 PRIOR p/m priority and GTIA mode $D21B 53275 GPRIOR $026F 623 PORTA port A $D300 54016 STICK0 $0278 632 STICK1 $0279 633 PORTB port B $D301 54017 STICK2 $027A 634 STICK3 $027B 635 PACTL port A control $D302 54018 PBCTL port B control $D303 54019 DMACTL Direct Memory access control (DMA) $D400 54272 SDMCTL $022F 559 CHACTL character control $D401 54273 CHART $02F3 755 DLISTL display list pointer low byte $D402 54274 SDLSTL $0230 560 DLISTH display list pointer high byte $D403 54275 SDLSTH $0231 561 HSCROL horizontal scroll $D404 54276 VSCROL vertical scroll $D405 54277 PMBASE player/missile address / 256 $D407 54279 CHBASE Address of character set / 256 $D409 54281 CHBAS $O2F4 756 WSYNC wait for horizontal sync $D40A 54282 VCOUNT vertical line counter $D40B 54283 PENH light pen horizontal position $D40C 54284 LPENH $0234 564 PENV light pen vertical position $D40D 54285 LPENV $0235 565 NMIEN non-maskable interrupt enable (NMI)$D40E 54286 NMIRES NMI reset $D40F 54287 NMIST NMI status $D40F 54287 SHADOW REGISTER ORDER ALPHEBETICAL ORDER Register Shadow Name Description Address Name Address ---------------------------------------------------------------------- KBCODE keyboard code $D209 53769 CH $O2FC 764 CHACTL character control $D401 54273 CHART $02F3 755 CHBASE Address of character set / 256 $D409 54281 CHBAS $O2F4 756 COLBK color/brightness of setcolor 4 $D01A 53274 COLOR4 $02C8 712 COLPF0 Color/brightness of setcolor 0 $D016 53270 COLOR0 $02C4 708 COLPF1 color/brightness of setcolor 1 $D017 53271 COLOR1 $02C5 709 COLPF2 color/brightness of setcolor 2 $D018 53272 COLOR2 $02C6 710 COLPF3 color/brightness of setcolor 3 $D019 53273 COLOR3 $02C7 711 PRIOR p/m priority and GTIA mode $D21B 53275 GPRIOR $026F 623 PENH light pen horizontal position $D40C 54284 LPENH $0234 564 PENV light pen vertical position $D40D 54285 LPENV $0235 565 POT0 game paddle 0 $D200 53760 PADDL0 $0270 624 POT1 game paddle 1 $D201 53761 PADDL1 $0271 625 POT2 game paddle 2 $D202 53762 PADDL2 $0272 626 POT3 game paddle 3 $D203 53763 PADDL3 $0273 627 POT4 game paddle 4 $D204 53764 PADDL4 $0274 628 POT5 game paddle 5 $D205 53765 PADDL5 $0275 629 POT6 game paddle 6 $D206 53766 PADDL6 $0276 630 POT7 game paddle 7 $D207 53767 PADDL7 $0277 631 COLPM0 color/brightness, player/missile 0 $D012 53266 PCOLR0 $02C0 704 COLPM1 color/brightness, player/missile 1 $D013 53267 PCOLR1 $02C1 705 COLPM2 color/brightness, player/missile 2 $D014 53268 PCOLR2 $02C2 706 COLPM3 color/brightness, player/missile 3 $D015 53269 PCOLR3 $02C3 707 IRQEN interrupt request enable (IRQ) $D20E 53774 POKMSK $0010 16 DLISTH display list pointer high byte $D403 54275 SDLSTH $0231 561 DLISTL display list pointer low byte $D402 54274 SDLSTL $0230 560 DMACTL Direct Memory access control (DMA) $D400 54272 SDMCTL $022F 559 SKCTL serial port control $D20F 53775 SSKCTL $0232 563 PORTA port A $D300 54016 STICK0 $0278 632 STICK1 $0279 633 PORTB port B $D301 54017 STICK2 $027A 634 STICK3 $027B 635 TRIG0 joystick trigger 0 $D010 53264 STRIG0 $0284 644 TRIG1 joystick trigger 1 $D011 53265 STRIG1 $0285 645 TRIG2 joystick trigger 2 $D012 53266 STRIG2 $0286 646 TRIG3 joystick trigger 3 $D013 53267 STRIG3 $0287 647 NUMERICAL ORDER IRQEN interrupt request enable (IRQ) $D20E 53774 POKMSK $0010 16 DMACTL Direct Memory access control (DMA) $D400 54272 SDMCTL $022F 559 DLISTL display list pointer low byte $D402 54274 SDLSTL $0230 560 DLISTH display list pointer high byte $D403 54275 SDLSTH $0231 561 SKCTL serial port control $D20F 53775 SSKCTL $0232 563 PENH light pen horizontal position $D40C 54284 LPENH $0234 564 PENV light pen vertical position $D40D 54285 LPENV $0235 565 PRIOR p/m priority and GTIA mode $D21B 53275 GPRIOR $026F 623 POT0 game paddle 0 $D200 53760 PADDL0 $0270 624 POT1 game paddle 1 $D201 53761 PADDL1 $0271 625 POT2 game paddle 2 $D202 53762 PADDL2 $0272 626 POT3 game paddle 3 $D203 53763 PADDL3 $0273 627 POT4 game paddle 4 $D204 53764 PADDL4 $0274 628 POT5 game paddle 5 $D205 53765 PADDL5 $0275 629 POT6 game paddle 6 $D206 53766 PADDL6 $0276 630 POT7 game paddle 7 $D207 53767 PADDL7 $0277 631 PORTA port A $D300 54016 STICK0 $0278 632 STICK1 $0279 633 PORTB port B $D301 54017 STICK2 $027A 634 STICK3 $027B 635 TRIG0 joystick trigger 0 $D010 53264 STRIG0 $0284 644 TRIG1 joystick trigger 1 $D011 53265 STRIG1 $0285 645 TRIG2 joystick trigger 2 $D012 53266 STRIG2 $0286 646 TRIG3 joystick trigger 3 $D013 53267 STRIG3 $0287 647 COLPM0 color/brightness, player/missile 0 $D012 53266 PCOLR0 $02C0 704 COLPM1 color/brightness, player/missile 1 $D013 53267 PCOLR1 $02C1 705 COLPM2 color/brightness, player/missile 2 $D014 53268 PCOLR2 $02C2 706 COLPM3 color/brightness, player/missile 3 $D015 53269 PCOLR3 $02C3 707 COLPF0 Color/brightness of setcolor 0 $D016 53270 COLOR0 $02C4 708 COLPF1 color/brightness of setcolor 1 $D017 53271 COLOR1 $02C5 709 COLPF2 color/brightness of setcolor 2 $D018 53272 COLOR2 $02C6 710 COLPF3 color/brightness of setcolor 3 $D019 53273 COLOR3 $02C7 711 COLBK color/brightness of setcolor 4 $D01A 53274 COLOR4 $02C8 712 CHACTL character control $D401 54273 CHART $02F3 755 CHBASE Address of character set / 256 $D409 54281 CHBAS $O2F4 756 KBCODE keyboard code $D209 53769 CH $O2FC 764 APPENDIX B OPERATING SYSTEM EQUATES 0100 ; 0101 ; ATARI 800 EQUATE LISTING 0102 ; 0103 ; 0104 ; 0105 ;This listing is based on the original release of Operating System, 0106 ;version A. The vectors shown here were not changed in version B. 0107 ;New equates for XL and XE models are included and noted. Changes 0108 ;from version B to XL/XE are also noted. 0109 ; 0110 ;Most of the equate names given below are the official Atari 0111 ;names. They are in common use but are not mandatory. 0112 ; 0113 ; 0114 ; DEVICE NAMES 0115 ; 0116 ; 0117 ;SCREDT = "E" SCREEN EDITOR 0118 ;KBD = "K" KEYBOARD 0119 ;DISPLY = "S" DISPLAY 0120 ;PRINTR = "P" PRINTER 0121 ;CASSET = "C" CASSETTE 0122 ;DISK = "D" DISK DRIVE 0123 ; 0124 ; 0125 ; 0126 ; STATUS CODES 0127 ; 0128 ; 0129 SUCCES = $01 1 0130 BRKABT = $80 128 BREAK KEY ABORT 0131 PRVOPN = $82 130 IOCB ALREADY OPEN 0132 NONDEV = $82 130 NONEXISTANT DEVICE 0133 WRONLY = $83 131 OPENED FOR WRITE ONLY 0134 NVALID = $84 132 INVALID COMMAND 0135 NOTOPN = $85 133 DEVICE OR FILE NOT OPEN 0136 BADIOC = $86 134 INVALID IOCB NUMBER 0137 RDONLY = $87 135 OPENED FOR READ ONLY 0138 EOFERR = $88 136 END OF FILE 0139 TRNRCD = $89 137 TRUNCATED RECORD 0140 TIMOUT = $8A 138 PERIPHERAL TIME OUT 0141 DNACK = $8B 139 DEVICE DOES NOT ACKNOWLEDGE 0142 FRMERR = $8C 140 SERIAL BUS FRAMING ERROR 0143 CRSROR = $8D 141 CURSOR OUT OF RANGE 0144 OVRRUN = $8E 142 SERIAL BUS DATA OVERRUN 0145 CHKERR = $8F 143 SERIAL BUS CHECKSUM ERROR 0146 DERROR = $90 144 PERIPHERAL DEVICE ERROR 0147 BADMOD = $91 145 NON EXISTANT SCREEN MODE 0148 FNCNOT = $92 146 FUNCTION NOT IMPLEMENTED 0149 SCRMEM = $93 147 NOT ENOUGH MEMORY FOR SCREEN MODE 0150 ; 0151 ; 0152 ; 0153 ; 0154 ; COMMAND CODES FOR CIO 0155 ; 0156 ; 0157 OPEN = $03 3 0158 OPREAD = $04 4 OPEN FOR INPUT 0159 GETREC = $05 5 GET RECORD 0160 OPDIR = $06 6 OPEN TO DISK DIRECTORY 0161 GETCHR = $07 7 GET BYTE 0162 OWRITE = $08 8 OPEN FOR OUTPUT 0163 PUTREC = $09 9 WRITE RECORD 0164 APPEND = $09 9 OPEN TO APPEND TO END OF DISK FILE 0165 MXDMOD = $10 16 OPEN TO SPLIT SCREEN (MIXED MODE) 0166 PUTCHR = $0B 11 PUT-BYTE 0167 CLOSE = $0C 12 0168 OUPDAT = $0C 12 OPEN FOR INPUT AND OUTPUT AT THE SAME TIME 0169 STATUS = $0D 13 0170 SPECIL = $0E 14 BEGINNING OF SPECIAL COMMANDS 0171 DRAWLN = $11 17 SCREEN DRAW 0172 FILLIN = $12 18 SCREEN FILL 0173 RENAME = $20 32 0174 INSCLR = $20 32 OPEN TO SCREEN BUT DON'T ERASE 0175 DELETE = $21 33 0176 DFRMAT = $21 33 FORMAT DISK (RESIDENT DISK HANDLER (RDH)) 0177 LOCK = $23 35 0178 UNLOCK = $24 36 0179 POINT = $25 37 0180 NOTE = $26 38 0181 PTSECT = $50 80 RDH PUT SECTOR 0182 GTSECT = $52 82 RDH GET SECTOR 0183 DSTAT = $53 83 RDH GET STATUS 0184 PSECTV = $57 87 RDH PUT SECTOR AND VERIFY 0185 NOIRG = $80 128 NO GAP CASSETTE MODE 0186 CR = $9B 155 CARRIAGE RETURN (EOL) 0187 ; 0188 IOCBSZ = $10 16 IOCB SIZE 0189 MAXIOC = $80 128 MAX IOCB BLOCK SIZE 0190 IOCBF = $FF 255 IOCB FREE 0191 ; 0192 LEDGE = $02 2 DEFAULT LEFT MARGIN 0193 REDGE = $27 39 DEFAULT RIGHT MARGIN 0194 ; 0195 ; OS VARIABLES 0196 ; 0197 ; PAGE 0 0198 ; 0199 LINZBS = $00 0 (800) FOR ORIGINAL DEBUGGER 0200 ; $00 0 (XL) RESERVED 0201 NGFLAG = $01 1 (XL) FOR POWER-UP SELF TEST 0202 CASINI = $02 2 0203 RAMLO = $04 4 POINTER FOR SELF TEST 0204 TRAMSZ = $06 6 TEMPORARY RAM SIZE 0205 TSTDAT = $07 7 TEST DATA 0206 WARMST = $08 8 0207 BOOT? = $09 9 SUCCESSFUL BOOT FLAG 0208 DOSVEC = $0A 10 PROGRAM RUN VECTOR 0209 DOSINI = $0C 12 PROGRAM INITIALIZATION 0210 APPMHI = $0E 14 DISPLAY LOW LIMIT 0211 POKMSK = $10 16 IRQ ENABLE FLAGS 0212 BRKKEY = $11 17 FLAG 0213 RTCLOK = $12 18 3 BYTES, MSB FIRST 0214 BUFADR = $15 21 INDIRECT BUFFER ADDRESS 0215 ICCOMT = $17 23 COMMAND FOR VECTOR 0216 DSKFMS = $18 24 DISK FILE MANAGER POINTER 0217 DSKUTL = $1A 26 DISK UTILITY POINTER (DUP.SYS) 0218 PTIMOT = $1C 28 (800) PRINTER TIME OUT REGISTER 0219 ABUFPT = $1C 28 (XL) RESERVED 0220 PBPNT = $1D 29 (800) PRINTER BUFFER POINTER 0221 ; $1D 29 (XL) RESERVED 0222 PBUFSZ = $1E 30 (800) PRINTER BUFFER SIZE 0223 ; $1E 30 (XL) RESERVED 0224 PTEMP = $1F 31 (800) TEMPORARY REGISTER 0225 ; $1F 31 (XL) RESERVED 0226 ZIOCB = $20 32 ZERO PAGE IOCB 0227 ICHIDZ = $20 32 HANDLER INDEX NUMBER (ID) 0228 ICDNOZ = $21 33 DEVICE NUMBER 0229 ICCOMZ = $22 34 COMMAND 0230 ICSTAZ = $23 35 STATUS 0231 ICBALZ = $24 36 BUFFER POINTER LOW BYTE 0232 ICBAHZ = $25 37 BUFFER POINTER HIGH BYTE 0233 ICPTLZ = $26 38 PUT ROUTINE POINTER LOW 0234 ICPTHZ = $27 39 PUT ROUTINE POINTER HIGH 0235 ICBLLZ = $28 40 BUFFER LENGTH LOW 0236 ICBLHZ = $29 41 0237 ICAX1Z = $2A 42 AUXILIARY INFORMATION BYTE 1 0238 ICAX2Z = $2B 43 0239 ICSPRZ = $2C 44 TWO SPARE BYTES (CIO USE) 0240 ICIDNO = $2E 46 IOCB NUMBER X 16 0241 CIOCHR = $2F 47 CHARACTER BYTE FOR CURRENT OPERATION 0242 ; 0243 STATUS = $30 48 STATUS STORAGE 0244 CHKSUM = $31 49 SUM WITH CARRY ADDED BACK 0245 BUFRLO = $32 50 DATA BUFFER LOW BYTE 0246 BUFRHI = $33 51 0247 BFENLO = $34 52 ADDRESS OF LAST BUFFER BYTE +1 (LOW) 0248 BFENHI = $35 53 0249 CRETRY = $36 54 (800) NUMBER OF COMMAND FRAME RETRIES 0250 LTEMP = $36 54 (XL) LOADER TEMPORARY STORAGE, 2 BYTES 0251 DRETRY = $37 55 (800) DEVICE RETRIES 0252 BUFRFL = $38 56 BUFFER FULL FLAG 0253 RECVDN = $39 57 RECEIVE DONE FLAG 0254 XMTDON = $3A 58 TRANSMISSION DONE FLAG 0255 CHKSNT = $3B 59 CHECKSUM-SENT FLAG 0256 NOCKSM = $3C 60 CHECKSUM-DOES-NOT-FOLLOW-DATA FLAG 0257 BPTR = $3D 61 0258 FTYPE = $3E 62 0259 FEOF = $3F 63 0260 FREQ = $40 64 0261 ; 0262 SOUNDR = $41 65 0=QUIET I/O 0263 CRITIC = $42 66 CRITICAL FUNCTION FLAG, NO DEFFERED VBI 0264 FMSZPG = $43 67 DOS ZERO PAGE, 7 BYTES 0265 CKEY = $4A 74 (800) START KEY FLAG 0266 ZCHAIN = $4A 74 (XL) HANDLER LOADER TEMP, 2 BYTES 0267 CASSBT = $4B 75 (800) CASSETTE BOOT FLAG 0268 DSTAT = $4C 76 DISPLAY STATUS 0269 ; 0270 ATRACT = $4D 77 0271 DRKMSK = $4E 78 ATTRACT MASK 0272 COLRSH = $4F 79 ATTRACT COLOR SHIFTER (EORed WITH GRAPHICS) 0273 ; 0274 TMPCHR = $50 80 0275 HOLD1 = $51 81 0276 LMARGN = $52 82 SCREEN LEFT MARGIN REGISTER 0277 RMARGN = $53 83 SCREEN RIGHT MARGIN 0278 ROWCRS = $54 84 CURSOR ROW 0279 COLCRS = $55 85 CURSOR COLUMN, 2 BYTES 0280 DINDEX = $57 87 DISPLAY MODE 0281 SAVMSC = $58 88 SCREEN ADDRESS 0282 OLDROW = $5A 90 CURSOR BEFORE DRAW OR FILL 0283 OLDCOL = $5B 91 0284 OLDCHR = $5D 93 DATA UNDER CURSOR 0285 OLDADR = $5E 94 CURSOR ADDRESS 0286 NEWROW = $60 96 (800) DRAWTO DESTINATION 0287 FKDEF = $60 96 (XL) FUNCTION KEY DEFINATION POINTER 0288 NEWCOL = $61 97 (800) DRAWTO DESTINATION, 2 BYTES 0289 PALNTS = $62 98 (XL) EUROPE/NORTH AMERICA TV FLAG 0290 LOGCOL = $63 99 LOGICAL LINE COLUMN POINTER 0291 MLTTMP = $66 102 0292 OPNTMP = $66 102 TEMPORARY STORAGE FOR CHANNEL OPEN 0293 SAVADR = $68 104 0294 RAMTOP = $6A 106 START OF ROM (END OF RAM + 1), HIGH BYTE ONLY 0295 BUFCNT = $6B 107 BUFFER COUNT 0296 BUFSTR = $6C 108 POINTER USED BY EDITOR 0297 BITMSK = $6E 110 POINTER USED BY EDITOR 0298 SHFAMT = $6F 111 0299 ROWAC = $70 112 0300 COLAC = $72 114 0301 ENDPT = $74 116 0302 DELTAR = $76 118 0303 DELTAC = $77 119 0304 ROWINC = $79 121 (800) 0305 KEYDEF = $79 121 (XL) KEY DEFINATION POINTER, 2 BYTES 0306 COLINC = $7A 122 (800) 0307 SWPFLG = $7B 123 NON 0 IF TEXT AND REGULAR RAM IS SWAPPED 0308 HOLDCH = $7C 124 CH MOVED HERE BEFORE CTRL AND SHIFT 0309 INSDAT = $7D 125 0310 COUNTR = $7E 126 0311 ; 0312 ZROFRE = $80 128 FREE ZERO PAGE, 84 BYTES 0313 FPZRO = $D4 212 FLOATING POINT RAM, 43 BYTES 0314 FR0 = $D4 212 FP REGISTER 0 0315 FRE = $DA 218 0316 FR1 = $E0 224 FP REGISTER 1 0317 FR2 = $E6 230 FP REGISTER 2 0318 FRX = $EC 236 SPARE 0319 EEXP = $ED 237 VALUE OF E 0320 NSIGN = $ED 237 SIGN OF FP NUMBER 0321 ESIGN = $EF 239 SIGN OF FP EXPONENT 0322 FCHFLG = $F0 240 FIRST CHARACTER FLAG 0323 DIGRT = $F1 241 NUMBER OF DIGITS RIGHT OF DECIMAL POINT 0324 CIX = $F2 242 INPUT INDEX 0325 INBUFF = $F3 243 POINTER TO ASCII FP NUMBER 0326 ZTEMP1 = $F5 245 0327 ZTEMP4 = $F7 247 0328 ZTEMP3 = $F9 249 0329 DEGFLG = $FB 251 0330 RADFLG = $FB 251 0=RADIANS, 6=DEGREES 0331 FLPTR = $FC 252 POINTER TO BCD FP NUMBER 0332 FPTR2 = $FE 254 0333 ; 0334 ; 0335 ; PAGE 1 0336 ; 0337 ; 65O2 STACK 0338 ; 0339 ; 0340 ; 0341 ; 0342 ; PAGE 2 0343 ; 0344 ; 0345 INTABS = $0200 512 INTERRUPT RAM 0346 VDSLST = $0200 512 NMI VECTOR 0347 VPRCED = $0202 514 PROCEED LINE IRQ VECTOR 0348 VINTER = $0204 516 INTERRUPT LINE IRQ VECTOR 0349 VBREAK = $0206 518 0350 VKEYBD = $0208 520 0351 VSERIN = $020A 522 SERIAL INPUT READY IRQ 0352 VSEROR = $020C 524 SERIAL OUTPUT READY IRQ 0353 VSEROC = $020E 526 SERIAL OUTPUT COMPLETE IRQ 0354 VTIMR1 = $0210 528 TIMER 1 IRQ 0355 VTIMR2 = $0212 530 TIMER 2 IRQ 0356 VTIMR4 = $0214 532 TIMER 4 IRQ 0357 VIMIRQ = $0216 534 IRQ VECTOR 0358 CDTMV1 = $0218 536 DOWN TIMER 1 0359 CDTMV2 = $021A 538 DOWN TIMER 2 0360 CDTMV3 = $021C 540 DOWN TIMER 3 0361 CDTMV4 = $021E 542 DOWN TIMER 4 0362 CDTMV5 = $0220 544 DOWN TIMER 5 0363 VVBLKI = $0222 546 0364 VVBLKD = $0224 548 0365 CDTMA1 = $0226 550 DOWN TIMER 1 JSR ADDRESS 0366 CDTMA2 = $0228 552 DOWN TIMER 2 JSR ADDRESS 0367 CDTMF3 = $022A 554 DOWN TIMER 3 FLAG 0368 SRTIMR = $022B 555 REPEAT TIMER 0369 CDTMF4 = $022C 556 DOWN TIMER 4 FLAG 0370 INTEMP = $022D 557 IAN'S TEMP 0371 CDTMF5 = $022E 558 DOWN TIMER FLAG 5 0372 SDMCTL = $022F 559 DMACTL SHADOW 0373 SDLSTL = $0230 560 DISPLAY LIST POINTER 0374 SSKCTL = $0232 562 SKCTL SHADOW 0375 ; $0233 563 (800) UNLISTED 0376 LCOUNT = $0233 563 (XL) LOADER TEMP 0377 LPENH = $0234 564 LIGHT PEN HORIZONTAL 0378 LPENV = $0235 565 LIGHT PEN VERTICAL 0379 ; $0236 566 2 SPARE BYTES 0380 ; $0238 568 (800) SPARE, 2 BYTES 0381 RELADR = $0238 568 (XL) LOADER 0382 CDEVIC = $023A 570 DEVICE COMMAND FRAME BUFFER 0383 CAUX1 = $023C 572 DEVICE COMMAND AUX 1 0384 CAUX2 = $023D 573 DEVICE COMMAND AUX 2 0385 TEMP = $023E 574 TEMPORARY STORAGE 0386 ERRFLG = $023F 575 DEVICE ERROR FLAG (EXCEPT TIMEOUT) 0387 DFLAGS = $0240 576 FLAGS FROM DISK SECTOR 1 0388 DBSECT = $0241 577 NUMBER OF BOOT DISK SECTORS 0389 BOOTAD = $0242 578 BOOT LOAD ADDRESS POINTER 0390 COLDST = $0244 580 COLD START FLAG, 1 = COLD START IN PROGRESS 0391 ; $0245 581 (800) SPARE 0392 RECLEN = $0245 581 (XL) LOADER 0393 DSKTIM = $0246 582 (800) DISK TIME OUT REGISTER 0394 ; $0246 582 (XL) RESERVED, 39 BYTES 0395 LINBUF = $0247 583 (800) CHARACTER LINE BUFFER, 40 BYTES 0396 CHSALT = $026B 619 (XL) CHARACTER SET POINTER 0397 VSFLAG = $026C 620 (XL) FINE SCROLL TEMPORARY 0398 KEYDIS = $026D 621 (XL) KEYBOARD DISABLE 0399 FINE = $026E 622 (XL) FINE SCROLL FLAG 0400 GPRIOR = $026F 623 P/M PRIORITY AND GTIA MODES 0401 GTIA = $026F 623 0402 PADDL0 = $0270 624 (XL) 3 MORE PADDLES, (800) 6 MORE PADDLES 0403 STICK0 = $0278 632 (XL) 1 MORE STICK, (800) 3 MORE STICKS 0404 PTRIG0 = $027C 636 (XL) 3 MORE PADDLE TRIGGERS, (800) 6 MORE 0405 STRIG0 = $0284 644 (XL) 1 MORE STICK TRIGGER, (800) 3 MORE 0406 CSTAT = $0288 648 (800) 0407 WMODE = $0289 649 0408 BLIM = $028A 650 0409 ; $028B 651 5 SPARE BYTES 0410 NEWADR = $028E 654 (XL) LOADER RAM 0411 TXTROW = $0290 656 0412 TXTCOL = $0291 657 0413 TINDEX = $0293 659 TEXT INDEX 0414 TXTMSC = $0294 660 0415 TXTOLD = $0296 662 OLD ROW AND OLD COL FOR TEXT, 2 BYTES 0416 ; $0298 664 4 SPARE BYTES 0417 TMPX1 = $029C 668 (800) 0418 CRETRY = $029C 668 (XL) NUMBER OF COMMAND FRAME RETRIES 0419 SUBTMP = $029E 670 0420 HOLD2 = $029F 671 0421 DMASK = $02A0 672 0422 TMPLBT = $02A1 673 0423 ESCFLG = $02A2 674 0424 TABMAP = $02A3 675 15 BYTE BIT MAP FOR TAB SETTINGS 0425 LOGMAP = $02B2 690 4 BYTE LOGICAL LINE START BIT MAP 0426 INVFLG = $02B6 694 0427 FILFLG = $02B7 695 FILL DIRING DRAW FLAG 0428 TMPROW = $02B8 696 0429 TMPCOL = $02B9 697 0430 SCRFLG = $02BB 699 SCROLL FLAG 0431 HOLD4 = $02BC 700 0432 HOLD5 = $02BD 701 (800) 0433 DRETRY = $02BD 701 (XL) NUMBER OF DEVICE RETRIES 0434 SHFLOC = $02BE 702 0435 BOTSCR = $02BF 703 24 NORM, 4 SPLIT 0436 PCOLR0 = $02C0 704 3 MORE PLAYER COLOR REGISTERS 0437 COLOR0 = $02C4 708 4 MORE GRAPHICS COLOR REGISTERS 0438 ; $02C9 713 (800) 23 SPARE BYTES 0439 RUNADR = $02C9 713 (XL) LOADER VECTOR 0440 HIUSED = $02CB 715 (XL) LOADER VECTOR 0441 ZHIUSE = $02CD 717 (XL) LOADER VECTOR 0442 GBYTEA = $02CF 719 (XL) LOADER VECTOR 0443 LOADAD = $02D1 721 (XL) LOADER VECTOR 0444 ZLOADA = $02D3 723 (XL) LOADER VECTOR 0445 DSCTLN = $02D5 725 (XL) DISK SECTOR SIZ 0446 ACMISR = $02D7 727 (XL) RESERVED 0447 KRPDER = $02D9 729 (XL) KEY AUTO REPEAT DELAY 0448 KEYREP = $02DA 730 (XL) KEY AUTO REPEAT RATE 0449 NOCLIK = $02DB 731 (XL) KEY CLICK DISABLE 0450 HELPFG = $02DC 732 (XL) HELP KEY FLAG 0451 DMASAV = $02DD 733 (XL) SDMCTL (DMA) SAVE 0452 PBPNT = $02DE 734 (XL) PRINTER BUFFER POINTER 0453 PBUFSZ = $02DF 735 (XL) PRINTER BUFFER SIZE 0454 GLBABS = $02E0 736 GLOBAL VARIABLES, 4 SPARE BYTES 0455 RAMSIZ = $02E4 740 PERMANENT START OF ROM POINTER 0456 MEMTOP = $02E5 741 END OF FREE RAM 0457 MEMLO = $02E7 743 0458 ; $02E9 745 (800) SPARE 0459 HNDLOD = $02E9 745 (XL) HANDLER LOADER FLAG 0460 DVSTAT = $02EA 746 DEVICE STATUS BUFFER, 4 BYTES 0461 CBAUDL = $02EE 750 CASSETTE BAUD RATE, 2 BYTES 0462 CRSINH = $02F0 752 1 = INHIBIT CURSOR 0463 KEYDEL = $02F1 753 KEY DELAY AND RATE 0464 CH1 = $02F2 754 0465 CHACT = $02F3 755 0466 CHBAS = $02F4 756 CHARACTER SET POINTER 0467 NEWROW = $02F5 757 (XL) DRAW DESTINATION 0468 NEWCOL = $02F6 758 (XL) DRAW DESTINATION 0469 ROWINC = $02F8 760 (XL) 0470 COLINC = $02F9 761 (XL) 0471 CHAR = $02FA 762 0472 ATACHR = $02FB 763 ATASCII CHARACTER FOR CIO 0473 CH = $02FC 764 0474 FILDAT = $02FC 764 COLOR FOR SCREEN FILL 0475 DSPFLG = $02FE 766 DISPLAY CONTROL CHARACTERS FLAG 0476 SSFLAG = $02FF 767 DISPLAY START/STOP FLAFG 0477 ; 0478 ; 0479 ; PAGE 3 0480 ; 0481 ; 0482 ; RESIDENT DISK HANDLER/SIO INTERFACE 0483 ; 0484 DCB = $0300 768 DEVICE CONTROL BLOCK 0485 DDEVIC = $0300 768 0486 DUNIT = $0301 769 0487 DCOMND = $0302 770 0488 DSTATS = $0303 771 0489 DBUFLO = $0304 772 0490 DBUFHI = $0305 773 0491 DTIMLO = $0306 774 0492 DBYTLO = $0308 776 0493 DBYTHI = $0309 777 0494 DAUX1 = $030A 778 0495 DAUX2 = $030B 779 0496 TIMER1 = $030C 780 INITIAL TIMER VALUE 0497 ADDCOR = $030E 782 (800) ADDITION CORRECTION 0498 JMPERS = $030E 782 (XL) OPTION JUMPERS 0499 CASFLG = $030F 783 CASSETTE MODE WHEN SET 0500 TIMER2 = $0310 784 FINAL VALUE, TIMERS 1 & 2 DETERMINE BAUD RATE 0501 TEMP1 = $0312 786 0502 TEMP2 = $0313 787 (XL) 0503 TEMP2 = $0314 788 (800) 0504 PTIMOT = $0314 788 (XL) PRINTER TIME OUT 0505 TEMP3 = $0315 789 0506 SAVIO = $0316 790 SAVE SERIAL IN DATA PORT 0507 TIMFLG = $0317 791 TIME OUT FLAG FOR BAUD RATE CORRECTION 0508 STACKP = $0318 792 SIO STACK POINTER SAVE 0509 TSTAT = $0319 793 TEMPORARY STATUS HOLDER 0510 HATABS = $031A 794 HANDLER ADDRESS TABLE, 38 BYTES 0511 MAXDEV = $0321 801 MAXIMUM HANDLER ADDRESS INDEX 0512 PUPBT1 = $033D 829 (XL) POWER-UP/RESET 0513 PUPBT2 = $033E 830 (XL) POWER-UP/RESET 0514 PUPBT3 = $033F 831 (XL) POWER-UP/RESET 0515 ; 0516 ;IOCB's 0517 ; 0518 IOCB = $0340 832 0519 ICHID = $0340 832 0520 ICDNO = $0341 833 0521 ICCOM = $0342 834 0522 ICSTA = $0343 835 0523 ICBAL = $0344 836 0524 ICBAH = $0345 837 0525 ICPTL = $0346 838 0526 ICPTH = $0347 839 0527 ICBLL = $0348 840 0528 ICBLH = $0349 841 0529 ICAX1 = $034A 842 0530 ICAX2 = $034B 843 0531 ICAX3 = $034C 844 0532 ICAX4 = $034D 845 0533 ICAX5 = $034E 846 0534 ICAX6 = $034F 847 0535 ; OTHER IOCB's, 112 BYTES 0536 PRNBUF = $03C0 960 PRINTER BUFFER, 40 BYTES 0537 ; $03E8 1000 (800) 21 SPARE BYTES 0538 SUPERF = $03E8 1000 (XL) SCREEN EDITOR 0539 CKEY = $03E9 1001 (XL) START KEY FLAG 0540 CASSBT = $03EA 1002 (XL) CASSETTE BOOT FLAG 0541 CARTCK = $03EB 1003 (XL) CARTRIDGE CHECKSUM 0542 ACMVAR = $03ED 1005 (XL) RESERVED, 6 BYTES 0543 MINTLK = $03F9 1017 (XL) RESERVED 0544 GINTLK = $03FA 1018 (XL) CARTRIDGE INTERLOCK 0545 CHLINK = $03FB 1019 (XL) HANDLER CHAIN, 2 BYTES 0546 CASBUF = $03FD 1021 CASSETTE BUFFER, 131 BYTES TO $047F 0547 ; 0548 ; 0549 ; PAGE 4 0550 ; 0551 ; 0552 USAREA = $0480 1152 128 SPARE BYTES 0553 ; 0554 ; SEE APPENDIX C FOR PAGES 4 AND 5 USAGE 0555 ; 0556 ; 0557 ; 0558 ; 0559 ; PAGE 5 0560 ; 0561 PAGE5 = $0500 1280 127 FREE BYTES 0562 ; $057E 1406 129 FREE BYTES IF FLOATING POINT ROUTINES NOT USED 0563 ; 0564 ;FLOATING POINT NON-ZERO PAGE RAM, NEEDED ONLY IF FP IS USED 0565 ; 0566 LBPR1 = $057E 1406 LBUFF PREFIX 1 0567 LBPR2 = $05FE 1534 LBUFF PREFIX 2 0568 LBUFF = $0580 1408 LINE BUFFER 0569 PLYARG = $05E0 1504 POLYNOMIAL ARGUMENTS 0570 FPSCR = $05E6 1510 PLYARG+FPREC 0571 FPSCR1 = $05EC 1516 FPSCR+FPREC 0572 FSCR = $05E6 1510 =FPSCR 0573 FSCR1 = $05EC 1516 =FPSCR1 0574 LBFEND = $05FF 1535 END OF LBUFF 0575 ; 0576 ; 0577 ; PAGE 6 0578 ; 0579 ; 0580 PAGE6 = $0600 1536 256 FREE BYTES 0581 ; 0582 ; 0583 ; PAGE 7 0584 ; 0585 ; 0586 BOOTRG = $0700 1792 PROGRAM AREA 0587 ; 0588 ; 0589 ; UPPER ADDRESSES 0590 ; 0591 ; 0592 RITCAR = $8000 32768 RAM IF NO CARTRIDGE 0593 LFTCAR = $A000 40960 RAM IF NO CARTRIDGE 0594 C0PAGE = $C000 49152 (800) EMPTY, 4K BYTES 0595 C0PAGE = $C000 49152 (XL) 2K FREE RAM IF NO CARTRIDGE 0596 ; $C800 51200 (XL) START OF OS ROM 0597 CHORG2 = $CC00 52224 (XL) INTERNATIONAL CHARACTER SET 0598 ; 0599 ; 0600 ; HARDWARE REGISTERS 0601 ; 0602 ; 0603 ; SEE REGISTER LIST FOR MORE INFORMATION 0604 ; 0605 ; 0606 HPOSP0 = $D000 53248 0607 M0PF = $D000 53248 0608 SIZEP0 = $D008 53256 0609 M0PL = $D008 53256 0610 SIZEM = $D00C 53260 0611 GRAFP0 = $D00D 53261 0612 GRAFM = $D011 53265 0613 COLPM0 = $D012 53266 0614 COLPF0 = $D016 53270 0615 PRIOR = $D01B 53275 0616 GTIAR = $D01B 53275 0617 VDELAY = $D01C 53276 0618 GRACTL = $D01D 53277 0619 HITCLR = $D01E 53278 0620 CONSOL = $D01F 53279 0621 AUDF1 = $D200 53760 0622 AUDC1 = $D201 53761 0623 AUDCTL = $D208 53768 0624 RANDOM = $D20A 53770 0625 IRQEN = $D20E 53774 0626 SKCTL = $D20F 53775 0627 PORTA = $D300 54016 0628 PORTB = $D301 54017 0629 PACTL = $D302 54018 0630 PBCTL = $D303 54019 0631 DMACLT = $D400 54272 0632 DLISTL = $D402 54274 0633 HSCROL = $D404 54276 0634 VSCROL = $D405 54277 0635 CHBASE = $D409 54281 0636 WSYNC = $D40A 54282 0637 VCOUNT = $D40B 54283 0638 NMIEN = $D40E 54286 0639 ; 0640 ; FLOATING POINT MATH ROUTINES 0641 ; 0642 AFP = $D800 55296 0643 FASC = $D8E6 55526 0644 IFP = $D9AA 55722 0645 FPI = $D9D2 55762 0646 ZFR0 = $DA44 55876 0647 ZF1 = $DA46 55878 0648 FSUB = $DA60 55904 0649 FADD = $DA66 55910 0650 FMUL = $DADB 56027 0651 FDIV = $DB28 56104 0652 PLYEVL = $DD40 56640 0653 FLD0R = $DD89 56713 0654 FLD0P = $DD8D 56717 0655 FLD1R = $DD98 56728 0656 FLD1P = $DD9C 56732 0657 FSTOR = $DDA7 56743 0658 FSTOP = $DDAB 56747 0659 FMOVE = $DDB6 56758 0660 EXP = $DDC0 56768 0661 EXP10 = $DDCC 56780 0662 LOG = $DECD 57037 0663 LOG10 = $DED1 57041 0664 ; 0665 ; 0666 ; OPERATING SYSTEM 0667 ; 0668 ; 0669 ; MODULE ORIGIN TABLE 0670 ; 0671 CHORG = $E000 57344 CHARACTER SET, 1K 0672 VECTBL = $E400 58368 VECTOR TABLE 0673 VCTABL = $E480 58496 RAM VECTOR INITIAL VALUE TABLE 0674 CIOORG = $E4A6 58534 CIO HANDLER 0675 INTORG = $E6D5 59093 INTERRUPT HANDLER 0676 SIOORG = $E944 59716 SIO DRIVER 0677 DSKORT = $EDEA 60906 DISK HANDLER 0678 PRNORG = $EE78 61048 PRINTER HANDLER 0679 CASORG = $EE78 61048 CASSETTE HANDLER 0680 MONORG = $F0E3 61667 MONITOR/POWER UP MODULE 0681 KBDORG = $F3E4 62436 KEYBOARD/DISPLAY HANDLER 0682 ; 0683 ; 0684 ; VECTOR TABLE, CONTAINS ADDRESSES OF CIO ROUTINES IN THE 0685 ; FOLLOWING ORDER. THE ADDRESSES IN THE TABLE ARE TRUE ADDRESSES-1 0686 ; 0687 ; ADDRESS + 0 OPEN 0688 ; + 2 CLOSE 0689 ; + 4 GET 0690 ; + 6 PUT 0691 ; + 8 STATUS 0692 ; + A SPECIAL 0693 ; + C JMP TO INITIALIZATION 0694 ; + F NOT USED 0695 ; 0696 ; 0697 EDITRV = $E400 58368 EDITOR 0698 SCRENV = $E410 58384 SCREEN 0699 KEYBDV = $E420 58400 KEYBOARD 0700 PRINTV = $E430 58416 PRINTER 0701 CASETV = $E440 58432 CASSETTE 0702 ; 0703 ; ROM VECTORS 0704 ; 0705 DSKINV = $E453 58451 0706 CIOV = $E456 58454 0707 SIOV = $E459 58457 0708 SYSVBV = $E45F 58463 0709 VBIVAL = $E460 58464 ADR AT VVBLKI 0710 XITVBV = $E462 58466 EXIT VBI 0711 VBIXVL = $E463 58467 ADR AT VVBLKD 0712 BLKBDV = $E471 58481 MEMO PAD MODE 0713 WARMSV = $E474 58484 0714 COLDSV = $E477 58487 APPENDIX C MEMORY USE Page 0 $00-$7F Operating system zero-page. The entire first half of page zero is reserved for the operating system. $80-$FF Free zero-page. The top half of page zero is free if BASIC is disabled. BASIC uses all but $CB-$D1. The floating point math routines use $D4-$FF. If the floating point arithmetic package is not used this memory is free. Page 1 $100-1FF This is the 6502 stack. The stack pointer initialized to $1FF and moves downward as the stack is filled. Pages 2-5 $200-$47F This area is used for operating system database variables. Parts which are not used in some particular programs, such as the cassette buffer or printer buffer, may then be used for other purposes. See the O.S. equate listing for these locations. $480-$57D ($480-$6FF if no floating point) This is called the user work space. It is free to be used by programs. If the floating point arithmetic package is not used the user work space extends to $6FF. This area is used by BASIC. $57E-$5FF This area is used by the floating point arithmetic package. It is free if the package is not used. Page 6 $600-6FF Atari has solemnly sworn never to put anything in this page of memory. Page 7-the screen region $700 This is called the boot region. Most machine language programs which don't use DOS load at this address. DOS extends from $700-$1CFB. MEMLO The address pointed to by the O.S. database variable MEMLO [$02E7,2 (743)] is the first byte of free memory. This pointer is usually changed by any program's initialization routine. For example, upon power-up, MEMLO points to $700. When DOS loads in, DOS changes MEMLO to point to $2A80. If an AUTORUN.SYS program then loads in just above DOS, such as DISKIO, it will usually change MEMLO to point above itself. One important reason for this is to protect the program from BASIC. BASIC uses memory starting at MEMLO. MEMTOP MEMTOP [$2E5,2 (741)] is set by the O.S. whenever a graphics mode is entered. The graphics region is at the very top of ram and extends downward. The address MEMTOP points to depends on how much memory the screen region uses. APPMHI APPMHI [$0E,2 (14)] should be set by any program to point to the highest address required by the program. If the O.S. cannot set up a screen without going below APPMHI it will return a not-enough-memory-for-screen-mode error. The cartridge slots $8000 (32768) This is the beginning of the 8K bytes used by the right cartridge slot of the 800. This is also where 16K cartridges begin. If there is no cartridge here it is ram. $A000 (40960) This is the beginning of the left cartridge of the 800 or the only cartridge slot on all other models. This is where the BASIC ROM resides in the XL/XE models. This area is RAM is there is no cartridge or BASIC is disabled on XL/XE models. above the cartridges $C000-$CFFF (49152-53247) This area is empty on the 800. Sometimes special ROM chips, such as Omnimon are wired in here. On the XL/XE models $C000-C7FF is free ram if there are no cartridges. On XL/XE models, the O.S. ROM starts at $C800 $D000-$D7FF (53248-57373) This area is taken up by the hardware chips. The chips actually take only a fraction of this space. If these addresses are further decoded there is space for many, many more hardware chips. For example, The PIA chip uses 256 bytes of memory but needs only 4 bytes. There is room for 64 PIA chips in this reserved memory. $E000-E3FF (57344-58367) This is the location of the ATASCII character set. $E400-FFF7 (58368-65527) This is the operating system ROM $FFF8-$FFFF (65528-65535) These last 8 bytes contain the addresses of the interrupt vectors. Upon power up the 6502 gets a reset pulse and looks up the reset routine here.