WTB: DEC Rainbow Expansion Memory

Warner Losh imp at bsdimp.com
Tue Apr 18 18:01:29 CDT 2017

Found this file on an old Rainbow floppy. It has more detailed data.


Sorry I didn't convert it to HTML...


On Sat, Apr 15, 2017 at 7:49 AM, Tapley, Mark via cctalk
<cctalk at classiccmp.org> wrote:
> On Apr 13, 2017, at 3:20 PM, Warner Losh via cctalk <cctalk at classiccmp.org> wrote:
>> On Thu, Apr 13, 2017 at 12:00 PM, shadoooo via cctech
>> <cctech at classiccmp.org> wrote:
>>> Hello,
>>> I'm in the pretty same condition, I have a Rainbow 100B without memory
>>> expansion.
>>> Not sure however, about the correct board number, which would fit the 100B.
>>> What should I search for?
>> The DEC part numbers for these are PC1XX-AY (128k) and PC1XX-AZ
>> (256k). I'm not sure what the board numbers are, and some auctions
>> list those instead.
>> They are the same board. There's 4 switches on the board. One for each
>> of the 3 banks to select between 64kbit chips and 256kbit chips. You
>> want 4164 or 41256 for the board. It's super easy to upgrade (I bought
>> a AY back in the day and then 18 months later I bought 27 41256 chips
>> and swapped them out in about 10-15 minutes.
>> I'm not sure what the 100A needs. I have no experience with the 100A hardware.
>> Warner
> I”m pretty sure the PC100A takes the same board. I believe I have a 100A set up like that, but I’ll have to check when I get back (from vacation) in a week or so (unless you get a definitive answer before that). Meantime if you spot one of those boards, obviously it would be good to grab it; sounds like there are 100B users on-list who would be happy to give it a home if I’m wrong about it working in the 100A.
>         Meantime, from my Rainbow Technical Manual copyright 1984 scan (ask, I have a fair number of these documents) which says it refers to model PC100A:
> Rainbow Memory Extension Option Installation Guide:    EK-PCMKE-IN
> …Two versions of the memory extension option are available: a 64 K byte option (part number PC1XX-AA) and a 192K byte option (part number PC1XX-AB). The memory option is installed in the J6 connector …
> …       Both versions of the memory extension option use the same printed circuit board etch and the same type of 6kK x 1 bit memory chips. … the 192K byte version contains twenty-seven 64K x 1 bit chips arranged as three 64K byte memory stacks. ...
>         From my Rainbow Owner’s manual 1st ed. Sept 1983, Appx. C, Table C-1
>> 64K byte memory board option:   PC1XX-AC
> 256K byte memory board option:  PC1XX-AD
> 64K byte memory component kit (9 chips) PC1XX-AY
> 256K byte memory component kit (9 chips)        PC1XX-AZ
>         Hope  this helps.

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