[Coco] [Color Computer] 1M simms in Cloud9 SIMM upgrade kit
lamune at doki-doki.net
Wed Jun 29 09:08:55 EDT 2005
I think you're right. I see a flaw in my theory but practical testing
seems to go with Paul on this one.
A 256k DRAM, although it's "9 bits per axis" actually only has 256
columns (8 bit refresh)
A 1M DRAM, whichi is "10 bits per axis" only has 512 columns (9 bit
I would still think that in theory you just don't use half of those
columns and the memory works fine. I ran the cloud9 memory test for
hours and hours and hours and everything tested fine.
I then ran the practical peripherals memory test just to verify my
results, and it reports errors with anything I test except 256k modules.
So, it's possible the algorithm in the first memory test was keeping
things refreshed but a more sophisticated test shows some errors.
It's too bad we can't hack that stupid GIME chip. there's plenty of time
to refresh a 1M chip as although there are twice as many columns to
refresh the time in which you have to refresh it is doubled.
Well it was an interesting experiment nonetheless!
Paul T. Barton wrote:
> Just let it sit for a minute or so,
> doing nothing, it may crash. My experience.
> Paul T Barton
> --- Mike Pepe <lamune at doki-doki.net> wrote:
>>I was going to send this over to Mark at cloud
>>9, but I figured I'd open it to the group.
>>I'm unsing a Cloud 9 512k SIMM upgrade board.
>>Then I got brave and installed a set of 1M 3
>>chip modules. They also
>>work! I've been running a memory test on it for
>>several hours and no problems reported.
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