30 Aug
2016
30 Aug
'16
9:18 a.m.
On Aug 30, 2016, at 3:07 AM, Mattis Lind
<mattislind at gmail.com> wrote:
You're talking about the Pro-380 daughtercard, right? It has a jumper on the card to
indicate to the software whether the card has 64k or 256k chips. I don't see anything
like that in the Pro-350 description.
The Pro 380 schematics have a tantalizing hint that the motherboard memory could be
populated with 256k memory chips. At least that's what the "memory jumper
configuration" note on sheet 4 of the PC380 system module schematics suggests.
Nothing else explains further, though.
The notes on the drawings also mention several different manufacturers, and the memory is
described as "MOS memory ... 150 ns".
It turns out the schematics I have are the "PC380 system module" portion of
what's already on Bitsavers in MP01922_PC380_EngrDrws_Jun84.pdf -- same revision. The
one extra bit of information is a hand-written note on the first sheet saying "these
schematics match Rev E1 etch 03-MAY-84"
paul
I misremembered the 350 (I don't have one): it can have memory in the I/O
card cage, but it also has memory daughter cards, two of them, with 40 pin
connectors.
Many years ago I upgraded those daughter cards and changed them from using
64kbit chips to 256 kbit chips. I don't remember the exact type which I
used. It was very successful. The system went from 512kbyte total to 1280
kbyte total. There were no stability issues what I remember so the refresh
seemed to have worked fine.