[Coco] hardware question - coco3 RAM subsystem

Stephen Adolph twospruces at gmail.com
Thu Mar 26 11:13:13 EDT 2009


Hi folks,
new to list, nice to meet you all.

Ok, here is my question.  Looking at the 512k upgrades for Coco3, I
understand this is a DRAM based system.

I happen to have a large amount of 2MB SRAMs, and a custom board with
a CPLD, that could be used to do a variety of things.

(actually it is a ReMem for the M100 - see www.istop.com/~sadolph - that's me.)
(I want to reuse some existing memory hardware to upgrade the COCO3 I have).


So, I am looking at the 41256 data sheet, and thinking about using
SRAM instead of DRAM.

But, 41256 has some memory modes "page mode" that allows the row to
remain while the column is stobed..to up the read/write rate I
presume.

Does COCO3 use these modes? OR, does it always operate in such a way
that CPU bus memory address always translates to one and only one
memory read/write?

OR, could I simply capture ROW and COLUMN and create my own address from that.

( I don't know enough about how the GIME chip manages the ram is what
this boils down to.)

pls advise if possible.

cheers,
Steve



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