Paul,
A couple of years ago I did design and build a new daughterboard with
modern SRAM that supports up to 2 MiB of RAM on the PC/380 and up to 512
KiB on the PC/350. https://oshpark.com/shared_projects/eBNkBw8x
It even works.
I never made a push to publish it because by the time I got to it the
parts (Cypress CY62167G-45ZXI SRAM and ATF1504AS-10AU100 CPLD) had
become unobtainable.
Maybe things have changed, but right now there are only 3 of these
boards. I have 2 and I think I sent the 3rd to you, Paul.
--Bjoren
On 7/29/2023 10:36 AM, Paul Koning via cctalk wrote:
On Jul 29, 2023, at 12:45 PM, Chris Zach via cctalk<[email protected]>
wrote:
Answering my own question: Yes it does work. My Pro/380 now sees 320kw of
memory instead of 256kw.
Now to buy some sockets and upgrade these boards to 256kw each. One can go in
the Pro/350 and the other plus the memory boards should take my Pro/380 to
almost 1kw.
I wonder if the CTI memory boards can be upgraded from 64k chips to 256k chips.
Probably would require reprogramming the ROM as well on the board. Hm.
The Pro Technical Manual (on Bitsavers) answers a bunch of these questions. If
I remember right, the 380 will accept 350 memory daugher cards but also
larger-capacity cards (bigger chips) that are 380 only. Also, the wiring for
the board allows for larger memories than what DEC actually built; the details
are in the CPU/Motherboard chapter of the manual. And/or in the schematics.
I've thought about building such a daughtercard, I think the best case allows
close to full 4 MB worth of memory.
paul
