WTB: DEC Rainbow Expansion Memory

[Warner Losh]

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