DEC Pro 350/380 Memory Cards - Interchangeability?

Mattis Lind mattislind at
Tue Aug 30 13:58:24 CDT 2016

> > I just looked up the tech manual page 5-46: "The system can address up to
> > 512kbytes per daughter board slot" so my memory wasn't that bad after
> all.
> Yes, indeed.  And the key item is shown on the daughtercard connector
> description: it has address lines 0..8, so 9 address bits, times 2 since
> DRAM has row and column addresses, that makes 256 k words.  What's
> different compared to the 380 is that there doesn't appear to be a signal
> that says which chip size is present, unless it's that "reserved" pin 39.
> The Pro 30 has pin 43, P256KD L, in other words, "this pin is connected to
> ground if the card has 256k chips on it".
> I wonder if those memory chips are still available.  Alternatively, I
> suppose one could emulate the whole daughtercard (the DRAM protocol and the
> memory too) in an FPGA.  :-)

There are 256 k chips (Intel & TI)  available from a Swedish surplus
seller. Similar type of chips show up on Ebay as well, for example this

>         paul

More information about the cctalk mailing list