> On Aug 30, 2016, at 1:02 PM, Mattis Lind <mattisl...@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.
>>
> No. Actually the 350. I still have the machine, though it hasn't been ran
> for ages. I did this "upgrade" more than 25 years ago so the (my...) memory
> is a bit fuzzy. But I think I remember that it was just a simple change of
> chips. No extra wiring needed to handle the extra address bit, it was all
> there.
>
> 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. :-)
paul
