29 Jul
2023
29 Jul
'23
5:57 p.m.
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<cctalk(a)classiccmp.org>
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
>
>