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Resources for your Atari 8-bit Computer

 

How to Tell if you have CTIA or GTIA

In early 1982, Atari began using an upgraded version of the CTIA chip called GTIA. GTIA stands for Graphics Television Interface Adapter, and CTIA means Color Television Interface Adapter. To find out if your Atari 400 or 800 computer has the newer GTIA chip, run the following BASIC program (don't forget to plug your BASIC cartridge into the left slot)...

10 GRAPHICS 9
20 GOTO 20

If you get a black screen, you have the newer GTIA chip. If you get a blue screen, you have the older CTIA chip.

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How to Tell if you have OS Revision A or B

In January of 1982, Revision B of the Operating System was released. To tell which version of the OS your machine has, type in this BASIC instruction (don't forget to plug your BASIC cartridge into the left slot)...

PRINT PEEK(58383)

If the result is 56 then you have Revision A
If the result is 0 then you have Revision B

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Which Version of BASIC do you have?

There are three versions of Atari BASIC for the 8-Bit computers. The 400 and 800 used either Version A or B on cartridge, the 800XL had basic built-in (usually Version B), and the 130XE had Version C built-in. Version C was also available on cartridge for the earlier models. You might be wondering how to tell which version you have, especially if it's on a cartridge. Here is some simple code to help, and of course, (don't forget to plug your BASIC cartridge into the left slot)...

PRINT PEEK(43234)

If the result is 162 then you have Version A
If the result is 96 then you have Version B
If the result is 234, you have Version C

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An Atari BASIC Line Deleter

If you've typed in many BASIC programs on your trusty old 8-Bit Atari, you no doubt have needed to delete a range of lines at one time or another. The hard way to do it is to manually type each line number, followed by RETURN. That's OK for 1 or 2 lines, but a real pain if you need to delete quite a few lines of code. Here's a handy little program to do it for you. It originated in one of the Atari magazines back in the early 80's. (Don't forget to plug your BASIC cartridge into the left slot)...

32761 GRAPHICS 0:POSITION 4,1:? "LINE DELETER":? :?
32762 ? "BEGINNING line number";:INPUT TOPLNO:? "ENDING line number";:INPUT BOTLNO:? "Intervals";:INPUT STPR
32763 FOR LINENO=TOPLNO TO BOTLNO STEP STPR
32764 ? CHR$(125):POSITION 2,4:? LINENO:? "CONT":POSITION 2,0:POKE 842,13:STOP
32765 POKE 842,12
32766 NEXT LINENO
32767 END

To use the Line Deleter:

1. Type in the listing and save it to disk or tape with the LIST command, not SAVE or CSAVE. (ex: use LIST"C:" for cassette or LIST"D:filename.ext" for disk.
2. When you're ready to use the Line Deleter, load it by typing ENTER"C:" for cassette or ENTER"D:filename.ext" for disk.
3. Type GOTO 32761.
4. The screen will prompt for three numbers: the beginning line number of the section to be deleted, the ending line number of the section to be deleted, and the intervals between lines.

Don't worry about the STOPPED AT LINE 32764 message or the flashing CONT on the screen, they're both perfectly normal while the program is running.

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GOTO the 8-Bit FAQ

For more information regarding Atari 8-Bit computers, please consult the official Atari 8-Bit Computers: Frequently Asked Questions

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GOTO the 8-Bit Reference Manual

For the advanced user (6502 assembly language knowledge a plus), try the 8-bit Reference Manual by Bob DuHamel.

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