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ChuckTeed

Chips for Atari Computers

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I bought an Atari computer lot last year, and finally got around to going through everything. When testing the computers (everything works!), I came across some chips that appear to be unused. Anyone able to give me details on them? I basically bought these to play games, but obviously the guy selling the stuff was doing more than playing the occasional game of Missile Command.

 

 

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Multiple 81256 - 256 Kilobit DRam chips. These are used in many computers such as some Amigas, STs, PCs of the day.

Generally the config is in groups of 8 or 16 as each chip provides 1 bit per byte or word accessed.

They were also used by some Atari 8-bit Ram upgrades, 256 + 64 gives 320K such as CompyShop or Rambo could have.

 

AR654 - Probably some internal part number. You'd probably do better searching on D2712BA.

I suspect maybe they're EPROMs.

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D27128A is an intel 16KB EPROM, pin compatible with the OS ROM chip in XL's and XE's, so it would be a quick test to swap them into a machine to see if they are by chance programmed with some alternate OS ROM. Otherwise, best to stick them on an EPROM programmer to read their contents. Nice thing is that even if you don't care what's on them, they should still be able to be erased and programmed again with something else.

 

As Rybags noted already the RAM chips could have been for planned memory upgrades, so may be worth checking if any of the A8 machines have any such upgrades already performed. The built in Self test won't reveal that, you'll have to try one of many other extended RAM testers to know, at least without opening them up and looking for modifications.

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you can use the 256k RAM chips in an atari 8bit. they will work fine but it will only use 64k max

these RAM chips can be used for an upgrade tho. for XL models, use a rambo board from bitsofthepast. for XE models search the internet or this forum for "atari 320xe mod" - its a bit more 'homebrew' than the rambo

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Thanks for the intel, everyone. Not sure what I'll do with them at this point; I have a local friend who might be interested in them, or I might just find a home elsewhere. I have so many more items to go through that I don't want to get too sidetracked by things I know little to nothing about!

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It's been a while, but I have been in communication with @ChuckTeed since this topic was started and have acquired his 2 Intel D27128A-2 EPROM's in question to read out and satisfy my curiosity. :)

 

Well, its somewhat anticlimactic - the one with a blank label has date code 8813 (Week 13 1988) and is indeed blank - all FF's, and a blank check in the minipro confirms.

 

The one labelled "AR654" has code, but I am unable to identify what it might be. It is not an Atari OS, nor an executable 16K atari cartridge ROM. The only string of recognizable text is near the end of the ROM: "CAXWIRQ" but it seems it might be from a system that uses 32-bit words, with some odd big-endian byte swapping going on because what looks like a sequential sweep through letters and numbers looks like this "89;:?><=67541023$%'&#" !*+)(-,./pqsrwvtu~.}|yxz{lmonkjhibca`edfg"...

 

Anyhow, curious if anyone else has any ideas of what this ROM might be...

 

Edit: now attached :)

AR654.BIN

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