The Atari 8-bit Hardware Upgrade, Modification and Add-On FAQ

The 6502 microprocessor at the heart of every Atari 8-bit has a sixteen bit wide address bus. What this means is that it can access up to 2^16 memory locations. That's 65536 bytes. Some people, wanting more memory, came up with a variety of techniques to use more memory. Most were built around the idea of bank switching. Bank switching means that you swap chunks of memory around so that the CPU can see them when necessary. Most schemes use 16k banks, though 4k and 32k have also been tried.

The original Atari 400 had either 8k or 16k. Atari produced a board with 48k. Mosaic produced a 32k board, as well as a 64k board with 48k RAM plus 4 4k RAM banks. (ANL 13, IFC)

The Atari 800 came with three memory slots. Each slot could contain Atari 8k or 16k RAM boards. Mosaic produced 32k and 64k boards. Three 64k boards could be combined for 192k.

Axlon produced the 128k RAMdisk board. It banks 16k, using $CFFF as a control register. Banked memory appears from $4000 to $7FFF.

David Byrd created the "800 PLUS 288K UPGRADE" which rewired existing 16k RAM boards, but required additional work to become fully Axlon compatible. A nasty sort of flame war erupted between David Byrd and Jay Torres of the Windhover Project over who invented the upgrade.

Magna systems produced 256k, 512k and 1M boards which followed the Axlon standard. (ANL 65, 68)

See 800xl.

As shipped, the Atari 600xl came with 16k RAM. Atari released the 1064 memory module which expanded the 600xl to 64k. MPP, now Supra, produced the Microram 64k Memory Board (ANL 19, 28)

RC Systems produced three expansion modules for the 600xl, raising memory to 32k, 48k or 64k (ANL 26, 12)

Richard Gore produced the Yorky, a 256k board which plugs in to the PBI. It provides full compatibility with 130xe type banking. It is for use on 600xls upgraded internally to 64k, or on 800xls. (AC 3/2, 10)

The 600xl can be internally upgraded to 64k by replacing the two RAM chips, and adding selects for the two address lines.

The Atari 800xl came with 64k RAM internal. To access RAM hidden under the OS ROMs, the PIA chip was used (PORTB, used for STICK(2) and (3) on the original 800). Claus Bucholtz published plans for a 256k upgrade which banked 32k at a time using PORTB for control in Byte magazine. (Byte Sept 85)

ICD released the RAMBO upgrade, providing 256k in 16k banks, using PORTB. Newell came out with the 256k XL, which would work on a 1200xl or 800xl, providing 256k total memory, . The two upgrades used different sequences to access their banks. (ANL 44, 115)

Charles Bucholtz updated his upgrade to use 16k banks after the release of the 130xe. Most of the 800xl upgrades can be made compatible with Antic banking. The only possible problem would be when Antic and the CPU are supposed to be using different memory banks.

The Yorky will also provide 256k on an 800xl (see the entry under 600xl).

Newell released 1Meg and 4Meg upgrades for the 800xl. These banked 16k as well, and required disabling internal BASIC to properly access the memory.

Fine Tooned Engineering, having bought the rights to ICD and Newell's products, is bringing out a third method in the Mars 8. Though not yet released, it will use SIMMs for 256k, 1Meg or 4Meg RAM.

The 800xl is arguably the most popular Atari 8-bit for upgrades, since most 800xls have socketed chips.

The 130xe was the first "official" method of banking memory. It too used PORTB, but with an added twist: ANTIC and the CPU could access different banks. This provided headaches for some owners of "older" 800xl upgrades, but few programs took advantage of this feature (SpartaDos Wedge and VideoBlitz demo only). Upgrades for the 130xe include replacing one set of 64k chips with 256k chips, raising the RAM to 320k. Adding another 256k for 576k total has also been done. These were designed by Scott Peterson, as was a 1088k upgrade.

The most common video upgrades are the SuperVideo series, described in AC 2/6. Plans were provided for the 600xl, 800xl, 1200xl and 130xe. The SuperVideo upgrade provides the forgotten chroma signal on the monitor port. It corrects a number of errors in the parts in the Atari video circuit, resulting in a clearer image, particularly on monitors.

Providing TTL output was also covered in AC 2/6. Bob Woolley provided plans for the circuit, as well as instructions for getting TTL output from an XEP80. Be warned that the output is not in the standard Atari colours; on a CGA type screen, the sixteen possible shades are translated into eight colours.

Since the 400/800 were released in 1979, people have been clamouring for better text displays than the default 40x24. Two products were released for the 800: The Austin-Franklin 80 column board and the Bit 3 80 column board were both for use in the Atari 800. They replaced the third memory module. The Austin-Franklin board came with a "Right Cartridge" which provided the drivers. Removing the cartridge disabled the board. Some software would not run with an 80-column board installed.

Ace 80/80xl was a cartridge released which provided 80 columns by using bitmapped graphics on an 80 column screen. A similar technique was used in the Newell Omniview, an add-on for their Omnimon.

Atari's entry into the 80 column field was the much maligned XEP80. For maximum compatibility, the XEP80 attaches to the computer via a joystick port. It includes three character sets, 8k internally, and a parallel printer port. The software provided by Atari supports a 320x200 graphics mode. This mode only supports direct bit images. Hacks have been released which hook the XEP80 on via the parallel bus.

Recent terminal programs have added two other display techniques. ICE-T uses a graphics 8 screen and fine scrolling for its display. FlickerTerm uses two graphics 0 screens a half-character apart, each displayed during alternate vertical blanks.

In a series of articles in the SLCC newsletter, Bob Woolley gave hardware plans for installing an 80-column TTL output inside an XL.

With the decline of Atari in North America, more and more quality software was migrating across the Atlantic which was all but unusable. Why? European Ataris are built for the PAL broadcast standard; North American Ataris use NTSC. Not knowing it was impossible, Nir Dary upgraded an NTSC Atari to run PAL software properly. Swap out the NTSC Antic chip for a PAL Antic, do a minor modification to the OS, and voila! Your Atari is ready to join the EU. (Better stop before the abbreviation police arrive!)

In October and November of 1991, Michael St Pierre published articles in the SLCC Journal describing plans for a monochrome Genlock. A genlock is a system to synchronize live video with a computer image. Graphics can be overlaid, faded in or out, or used for titling.

In 1994, Michael announced Prism Studio, a full colour genlock. It is sold by Mytek.

Computer Eyes was a video capture system which plugged into two joystick ports. It could render images in a variety of modes. It required a composite video source. (ANL 35, 53)

Take a cartridge, add a fibre-optic cable, and hook it onto a printer, and you've got Easy-Scan, an image scanner for the Atari 8-bit. Innovative Concepts produced this item. (ANT 7/6, 43)

Covox sold the Voice Master and Voice Master junior. These would capture and record speech. Bundled software attempted recognition of commands, with limited success. (ANL 47, 44)

The Parrot was a sound digitizer sold by Alpha Systems. Resembling a paddle, the device had phono jack for input. Antic provided plans for a similar project, called the Antic Sampling Processor. (ANT 8/8, 11)

Among the more esoteric products ever released was the SoundMouse, which interpreted sound to provide a reading on a paddle register. It did not act as a digitizer, like the Voice Master and Parrot did. Bundled software made the lava lamp look mainstream in its appeal. No commercial applications taking advantage of this unique device were released.

Chuck Steinman of DataQue created this set of plans for building stereo sound by installing a second Pokey chip (Pokey and Gumby, get it?). Once installed, the second channel has all its addresses 16 bytes higher in memory ($D210 - $D21F). A small number of demos have been released in stereo.

Lee Brilliant, ANALOG's resident hardware guru, came up with this system for stereo sound, running it off the clock line on the SIO bus. As with Gumby, it requires customized software to use. (ANL ???)

MIDI stands for Musical Instrument Digital Interface. It is a system for computers to record, replay and control musical instruments. MIDIMATE, when combined with MidiTrack software, permits an Atari 8-bit to take control. Why buy an ST? (ANL 33:26)

This is a set of plans to make your own MIDI interface. Limited software is included.

There was also a midi interface made by Wizztronics, called the MidiMax. Unlike the MidiMate, it had not jacks for external sync, but it did have an additional SIO port so it could be chained. It contained the same optoisolators generally used in midi keyboards, and the case was riveted steel -- real rugged. It came with Lee Actor's MMS software, some sample songs, a program to convert AMS to MMS files, and a couple of six foot midi cables. Gary Levenberg wrote the manual for the software. In addition, Wizztronics sold a dozen or so double-sided disks of MMS songs that had been converted from AMS.

Atari users were notorious for their software piracy. The Happy Drive (originally for the 810, later for the 1050) contributed to that reputation. It was a modified 810, which could duplicate copy protected software. Thus began a war between crackers and software houses. It also included a full track buffer, which sped up operations and reduced the painful grinding sound of the 810 at work. The 1050 version also made the 1050 into a true double-density drive; version 7.0 would let the modified 1050 read and write 180k MS-DOS disks.

The Atari 1050 drive was brain-damaged from the very beginning. Rather than add a few dollars worth of parts to make a true double-density drive, Atari invented their own format, called "dual-density", which stored 130k on a disk. ICD produced the US Doubler, a hardware add-on that gave the 1050 true double-density. As an added bonus, it also included UltraSpeed, which made "the normal beep-beep of Pokey sound like staccato machine gun fire" according to one review. These drives, in order to use warp-speed, had to have disks formatted in a special "Ultra-speed" sector skew. Unlike the Happy which would buffer the whole track and warp it to the computer, the USDoubler had limited ram and relied on the sector to be accessible right when it needs to be read. Using a ultraskew disk in non-US mode was REALLY SLOW :) A variant was produced which added 4 to the drive number, permitting drives to be addressed as D5:-D8:.

This was CSS's entry into the 1050 DD sweepstakes. It included a high-end crackers' toolbox, letting you edit sectors, create phantom sectors and other fun stuff.

Eventually, software companies came up with a new copy-protection technique: use 34 sector tracks and repeating sector numbers, so you get a "different" sector #7 depending on where the disk is when you ask for it. CSS to the cracker's rescue again! The Bit-Writer reads in tracks from the disk and stores the bit pattern. This can then be re-written. Ironically, the software disk that came with this upgrade to the Super Archiver was created on a non-Atari machine, so users couldn't copy it.

Atari's last disk drive for the 8-bit wasn't quite perfect. This replacement OS ROM from CSS fixed a number of bugs (can't switch back and forth between SD and DD properly), and sped up the drive. A warning on upgrading the XF551: The main PC board is lousy. It's REALLY easy to break traces - even unplugging SIO cables can do it. BE CAREFUL!

CSS introduced these for the XF551. You could either replace the 360k mechanism with a 720k one, or add a 720k to the 360k. Software included let you read and write IBM disks.

Once again, someone couldn't leave well enough alone, ripped apart Atari hardware, got bored with merely improving the OS ROM, and swapped out the 360k 5 1/4" mechanism for a 720k 3 1/2" one. This was sold by an outfit called Innovative Concepts.

From Klaus Peters in Germany, this system provides a solid-state alternative to floppy and hard disks. Using up to 8 27512 EPROMs, this setup provides high-speed PBI access to commonly used software

Amdek released a new standard for disks: a rigid 3" plastic disk that could store a whopping 360k (but you'd have to flip the disk for that). It never caught on.

ICD manufactured this wonderboard in 1987. Connected to the PBI or ECI, it provided either 256k or 1Meg of RAM, an RS232 port, a parallel printer port and a SCSI hard drive port. The RAM can be configured as a RAMdisk or printer buffer, or via software as a hard disk cache. To connect it to a 130XE ECI required a special adapter that would convert the 130xe's cartridge/ECI to an 800XL compatible PBI. The little board had two cartridge slots (the rear of the two works for some cartrige types only, like Rtime 8) This looked better than having a tower of stackable cartriges coming out of your 800XL! (Spartados X, Rtime8, and Action all plugged on top of each other is rather obtrusive on an 800XL :)

Announced, sold but never delivered by Fine Tooned Engineering, this PBI/ECI board will provide an interface and power supply for an IDE hard disk. It may also include extended memory support for CPU upgraded computers, as well as a parallel port. It was demonstrated at the TAF show in 1995.

CSS manufactures the Black Box, a PBI/ECI device that offers an optional 64k printer buffer. Its main attractions are its m/l monitor, 19200 baud RS232 port, parallel port, and hard disk interface. The parallel and serial ports do not use standard DB9 or DB25 connectors; custom cables are required.

This is an add-on to the Black Box, also from CSS. It permits standard floppy drives, 360k, 720k, 1.2M and 1.44M, to be attached to the Black Box. Since they are connected to the PBI, these drives operate extremely quickly. Software included lets you read and write to MS-DOS format disks.

Supra released one of the first hard drives for the 800xl. It hooked up via the PBI. KP bought the rights to the interface from Supra.

The earliest hard disk interface, the Corvus system hooked up to a 400/800 via joystick ports 3 and 4. A custom DOS would be booted from a floppy disk to permit the computer to access the hard disk, which was divided into 720 sector partitions.

Some guys are constantly hacking hardware. And then there's Bob. Memory upgrades? PBIs for 1200xls? 80 column devices? Battery-backed RAM operating system? Somewhere, after all those, he found the time to interface the xl/xe parallel bus with an IDE hard drive. Plans to be published in the next Atari Classics magazine.

SWP Computer Products made this original wonder-widget: Serial and parallel ports, standard floppy interface, optional hard disk interface and even CPM and MS-DOS add-ons.

A long time ago, in a galaxy far, far away, was a mystic operating system known as CPM. A company named USS Enterprises produced the Critical Connection, a device to permit a CPM computer to emulate disk drives for the Atari. It was a cable, plus software for the CPM end of the system. The CPM system could also act as a printer buffer, and the CPM keyboard could be used in the place of the Atari keyboard. (ANL 39,103)

With the demise of CPM and the rise of the IMI cartel (IBM-Microsoft-Intel) a new system similar to the Critical Connection arose. Nick Kennedy developed the SIO2PC hardware and software, which permits any PC with a serial port to act as up to four disk drives for an Atari. It can also act as a printer buffer.

In ANL 59,60 and 62, Dr. Lee S. Brilliant provided plans and software to turn a surplus Atari into a printer buffer for another Atari. He called it "The Atari Zucchini".

The Printer Buffer Routine (PBR) and Disk Emulator Routine (DER) came from B.L. Enterprises. They were cartridges and cables which worked in a similar fashion to the Zucchini. The PBR provided a buffer, while the DER emulated a disk drive on the remote computer. Stock XLs gave 403 free sectors; a 130xe would give 914. (ANL 65, 67)

With the use of PORTB for RAM banking, hackers were looking for more parallel outputs. This plan, for adding one more PIA chip, includes notes for adding two more. It was intended as a means to control large RAM upgrades. (AIM 3/2, 16)

This radio station, when automating 6 broadcast hours daily, created a hardware and software package built around a 130xe for control. Control was via joystick ports and tone decoders. (ANT 8/7, 30)

This provided 8 or 16 channels and 2 or 4 sensors. It would monitor the temperature, with options to log results to disk or printer, or to sound an alarm if the temperature strayed out of set boundaries. The software was described as "cumbersome". (ANL 48, 35)

During one of their periodic restructurings, Atari decided to sell their computers as educational. Thus, the Atari Lab series was produced. The two kits released provided experimenters with tools to measure light and temperature, hooked in by the joystick ports. Of course, the next restructuring left this an orphan product.

Released by DataQue, this provided a replacement OS as well as a replacement for the 6502 CPU. A 65816 was substituted, providing new opcodes and a 24 bit address space (16Megs vs 64k with the 6502).

Released by Fine Tooned Engineering, this provides a 65816 CPU to replace the 6502. Documentation and software were supposed to follow; I bought #2 or #3 and am still waiting...

Notice one name popping up again and again? In AC 3/3, Bob began explaining how to add a 14 mHz 65816 to your xl. That's right, parallel processing. Complete plans were never published.

Supra provided the Atari community with its first networking product. MicroNet provides nine SIO connectors. Eight are for computers. The ninth goes to whatever peripherals are to be connected. The system served to isolate the computers electrically. It did no software checking, meaning that two or more users attempting to print or save at the same time could trash each others output. (ANL 51, 76)

CSS provided a better way to network. The Multiplexer system requires one host system which has all the disk drives and printers for the network. The slaves are connected via the cartridge port to the host, and all their disk and printer i/o is rerouted to the host. All the systems involved require their OS replaced with a special multiplexer OS. The only thing not shared by the network is the R: device, allowing the system to be used for running a multi-line BBS with BBS Express! Professional BBS software from K-Products, which is still actively supported. This was possible with a special version of 4.0, and is built into 5.0.

The most recent innovation in networking the 8-bit Atari, GameLink II permits up to 8 machines to share information for interactive games. Currently, only the Maze of Agdagon supports this system. DataQue sells cables and the game.

Released to on-line services and possibly to the Umich archive as well, this set of programs was designed to interface computers by the joystick port, using 3 bi-directional data lines and two control lines.

Even the most dedicated of Atari enthusiasts hates the xe keyboard, with its mushy feel. Michael St Pierre created an interface for a PC keyboard. Hook it in to your xl/xe, and plug in your PC keyboard. It includes programmable macro keys and a number of other features. Be warned that the PC keyboard isn't mapped the same as the Atari; for example, on the Atari SHIFT-2 gives a ", while on the PC it gives a @. Available from Dataque.

This keyboard was a full stroke replacement for the Atari 400 membrane keyboard, but they were very low keys....the touch was OK, but not excellent. There were better keyboard replacements for the 400, but NONE of them fit as well, or looked as if they were part of the orginal Atari 400.

The XE computers have arguably the worst keyboards ever made. To firm up the squishy keys, Best Electronics sells this set of silicone switches. It only works on one of the two xe keyboard models, though.

Huge RAM upgrades are great, but when your system crashes you can say goodbye to all the info in your RAMdisk. Bob Woolley made this mod to add a hard reset, by fooling the system into thinking that a cart had been pulled out of the system. Your system reboots, but your RAMdisk contents are preserved.

This is a clock cartridge for any Atari from Fine Tooned Engineering. It includes a pass-through connector so that any other cartridge can be plugged in as well. Though primarily intended for SpartaDos, software for other DOSes is included.

Announced 'way back in Atari Classics 1/1, this product was intended as a replacement for the R-Time 8 from Best Electronics. Software difficulties have kept it from being released.

This was under development from Fine Tooned Engineering. For 800xls only. Memory expansion of 256k, 1M or 4M using 30 pin SIMMs. Install internally Action, Basic XL/XE, MAC/65, SpartaDos X, R-Time 8. Shown at the TAF show in 1995, it was never commercially released.

This device hooks into the SIO line, and provides 4 9-pin RS232 ports and a 15-pin parallel port. The RS232 ports are NOT IBM PC standard. The MIO and PR Connection use the same pinout.

This device plugs into the SIO line, and provides 2 9-pin RS232 ports and a 15-pin parallel port. It is powered by the SIO line. The Atari 1200xl requires an internal modification to work with this device, or with the Atari XM301 300 baud modem.

With 850s and P:R: Connections becoming increasingly rare, Kenneth Siders released plans to build a high-speed serial interface using only 2 ICs.

Ever look in the back of an Apple II or an IBM PC, and envy the expansion cards? Atari was planning to release a similar expansion box. The full specs were written up, and prototypes were sent out to hardware developers. As usual, Atari took this great idea, buried it, and forgot about it. Add on cards included CPM and 64k RAM. These are EXTREMELY rare; I've only ever seen two for sale. Definitely collectors pieces.

The joystick port is a parallel port. The SIO port is a serial port. So where would you hook up a serial modem? MPP (now Supra) plugged a 300 baud modem into the joystick port. Running at 300 baud, with software that couldn't d/l files longer than 32k (an Xmodem bug), this is what got me started in the on-line world, and what got Supra started in the modem business. Wonder if I could trade in my old 300AT for a new 33.6k?

Manufactured by the ALIEN Group, this speech synthesizer even made it into TIME Magazine in their "Machine of the Year" issue in 1982. Plugging into the SIO line, this device would produce speech of the traditional computer variety.

Protronics of California announced this 128k RAMdisk/printer buffer which interfaced via the joystick ports, offering it as a replacement for the 850. A 512k upgrade was promised. (ANT 2/8, 106)

Newell Industries announced this 850 replacement in 1983. It offered two serial and one parallel port, along with an expandable 8k printer buffer. (ANT 2/8, 106)

This bar-code scanner was from the Databar Corp. The intent was to permit the speedy entry of computer programs which would be encoded in magazines. (ANT 2/8, 107)

Hackers love the 1200xl for two reasons: because of all the space available within the case, and because of the great keyboard. Bob Woolley came up with this set of plans for adding a parallel bus interface to the 1200xl.

ANALOG magazine provided this unique information on interfacing an 8-bit to a Radio Shack Armatron remote controlled arm. Positioning was determined using the paddle/potentiometers, and control was via the PIA (joystick pins).