WTB: DEC Rainbow Expansion Memory

[Stephen Pereira]

I guess it doesn’t make any difference now.  I reassembled the computer and now I get a message 28 “RX50 Controller Board" failure during POST. 
I’ve taken it apart and put it back together several times, but I cannot clear the failure.  This really has been a bad day!

smp
--
Stephen M. Pereira
Bedford, NH  03110
KB1SXE

> On Apr 12, 2017, at 3:07 PM, Warner Losh <imp at bsdimp.com> wrote:
> 
> On Wed, Apr 12, 2017 at 1:00 PM, Stephen Pereira
> <spereira1952 at comcast.net> wrote:
>> Thanks for your response.
>> 
>> Just to be certain, I just tore it all down and reconfirmed, in case my
>> memory was playing any tricks.
>> 
>> I have a PC-100B with no expansion card.
>> 
>> Thanks again for the advice.
> 
> Bummer. The cards come up from time to time in different places, but
> there's none on ebay right now. Last summer there were like 5,
> including one that had an 8087 coprocessor option...
> 
>> smp
>> --
>> Stephen M. Pereira
>> Bedford, NH  03110
>> KB1SXE
>> 
>> On Apr 12, 2017, at 2:20 PM, Warner Losh <imp at bsdimp.com> wrote:
>> 
>> On Wed, Apr 12, 2017 at 11:06 AM, Stephen Pereira via cctech
>> <cctech at classiccmp.org> wrote:
>> 
>> I’m looking for expansion memory for my DEC Rainbow.
>> 
>> I currently have 128K RAM, and I’d like to have 256K RAM, so I can actually
>> use the Lotus 1-2-3 that I recently purchased (without thinking).
>> 
>> Any suggestions?
>> 
>> 
>> So is this a 100A with a 64k expansion card? Or is it the 100B with no card?
>> 
>> If you have the 100A and a 3-bank expansion card, you should be able
>> to remove the 64k chips that are on there and replace them with 256k
>> chips. You should be able to take it to 832k with 27 256kbit DRAM
>> chips. 41256-120's in DIP 16 if I recall correctly. Need to set the
>> DIP switches correctly. This is the easiest path forward, if you are
>> lucky enough to have this configuration, since chips are easy to get,
>> relatively speaking, and last time I priced them, they were ~0.70 each
>> so this will set you back ~$20 from JAMECO. You'll want an anti-static
>> setup to do this, since the BBSs were full of people that had done
>> this w/o adequate setup blowing up their card / chips. IMHO, if you
>> are going this route, it's not worth messing with 64k chips since the
>> price difference is tiny and the win for 3 banks of 256k on the
>> Rainbow is big.
>> 
>> If you have a 100B with no expansion card, I can't help... The
>> expansion card is the hard bit these days...
>> 
>> Warner
>> 
>>