[Coladam] Disk Drive ROM

John Turner gimechip at live.com
Sun Mar 18 08:18:31 CET 2012

Well, I just took apart one of my Coleco Disk drives. Now, this thing was sold to me as working, but upon inspection I noticed one of the screws missing from the bottom. That's a bad sign I thought. Upon opening the thing up, I notice the 34 pin cable isn't even plugged in - no way this thing works. Looks like a repair project is in order... Anyway, the ROM in this one is actually an EPROM - an AMD 2732. I would not have thought that Coleco would have used EPROMs in production drives, given they eventually forget their data. Sure, it usually takes 20 years or so, but still... perhaps this is a 3rd party ROM? It has a sticker labelled:
AD 31 REV.A 9-27-84. I've dumped the ROM to my PC. Bytes 0-7FF are blank (all FF's) and bytes at addresses $800-$FFF contain data. This would seem that the first 2K of the ROM is blank and the last 2K contains data. Now, since a 6801 contains an internal 2K of ROM, it makes absolutely no sense to use an internal ROM for 2K of storage Unless Coleco used the internal 2K and needed an additional 2K. Looking at the 6801 I cannot confirm that it is a 6803 as I thought as it is a custom COLECO chip - this leads me to believe that it is in fact a mask programmed 6801 made for coleco and must contain 2K of the operating program within. Can anyone confirm this? Thanks - John

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