[Coladam] Disk Drive ROM

Jim Notini jnoti2 at comcast.net
Sun Mar 18 19:58:58 CET 2012


Getting back to a comment you made in a previous message about buying four 
disk drives... I figured someone was "getting their ADAM ON" !  ;- )

As far as this first drive, it definetly sounds like someone opened her up 
to inspect the internals, probably to see if there was something obvious 
that needed repair or just to clean. Hopefully it was just an effort to 
clean the drive and not something more major. As far as the ROM being an 
EPROM, I can't answer this one definitively as to whether MPI Technologies 
would have done this, but it DEFINITELY would be an original to the drive 
since the label is dated 1984. There was not any third party/homebrew 
development going on at this time as far as I know and the first updated 
firmware PROMS didn't come about until 1986 by Eve Electronics, then 
followed in 1987 by Orphanware and then 1988 by E&T Software/M.M.S.G. The 
last one by E&T/MMSG is THE one that you want seeing as Jim Marshall of MMSG 
completely disassembled the original firmware and made a number of 
improvements, corrections as well as added support for Double-Density and 
Quad-Density formats for drive upgrades.

As far as the rest of your message, way above the scope of my knowledge. 
Hopefully Dale Wick or Rich Drushel can chime in to aid you in your 
endeavor.

----- Original Message ----- 
From: "John Turner" <gimechip at live.com>
To: <coladam at adamcon.org>
Sent: Sunday, March 18, 2012 2:18 AM
Subject: [Coladam] Disk Drive ROM


>
> 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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