Re: XRAM notes

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From: Julian Perry jp@digitaltapestries.com
Reply: cbm-hackers@musoftware.de cbm-hackers@musoftware.de
Date: 2014-03-11 at 02:14:32
To: cbm-hackers@musoftware.de cbm-hackers@musoftware.de
Subject:  Re: XRAM notes

> My recollection of XRAM is that it's just self-refreshing/multiplexing DRAM,
> designed to be used as a cheap, pin-compatible replacement for SRAM, but needing a
> separate clock for refresh, and a longer reset. When I was doing all
> the investigation/work on DolphinDOS, I recall seeing a memory
> expansion board for the 1541 that had an Xram option on it. It just
> needed one additional wire, from memory.
> I think it was a variant of the RAMBOarD -
> http://www.lb.shuttle.de/puffin/8k1541/8k1541.html - I MIGHT still
> have the schematics somewhere - I'll look later.

There is something like this one:

http://www.d81.de/CLD-RAMBOard/orig/RAMBOard-1541-II-020sch.png

As I wrote still in June 2013: "According to the doc and schematic above, _RFSH is [..] :-) to be connected to PHI2 and one more cap for delaying the _OE/_CE lines should be added. I did so and it still doesn't work. I even connected CS to PHI2 as in the schematic, although I don't think it to make a difference."

--  
SD!

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