[Coco] 512k upgrade for coco3

Walter Miraglia walter.miraglia at gmail.com
Thu Sep 24 20:32:55 EDT 2015


Ok I thought so,  but i was looking at the schematic and thought, perhaps
because the ram in my 512k upgrade was dynamic, it too required the little
caps to remain... i was just looking for a reason as to why the 512k ram up
grade i have is flakey :)

ok i will have to pursue other avenues...

ok i wont have to order 82pf caps unless i give up on 512k :)

thanks for your reply. :)

On Thu, Sep 24, 2015 at 8:26 PM, David Ladd <davidwladd at gmail.com> wrote:

> There are two caps that need to be removed for any upgrade to 512K, 1M, 2M,
> those rare larger boards.
>
> Those two caps are only required if using the base 128K.
>
> On Thursday, September 24, 2015, Walter Miraglia <
> walter.miraglia at gmail.com>
> wrote:
>
> > Hi there.   I am wondering,  if I am upgrading my coco3 with an older
> dual
> > 30 pin sim based upgrade that uses dynamic ram sims, do I need to remove
> > the two small caps (82 and 27 pf caps on the RAS and CAS lines)?  Or is
> > that only for the 512k static ram upgrades triad one?
> >
> > I wonder as I am having issues with an old ram upgrade where basic ram
> > tests seem to pass but more involved use of ram, running applications
> like
> > donkey kong seem to crash.   I did remove those two caps and installed my
> > 512k dram based ram upgrade.  I'm wondering if I should have left them?
> > Should I solder in a couple and try it again?  ( I would have to order
> some
> > )
> >
> > Please advise.  Any help appreciated.
> >
> > Sent from my iPad Mini
> >
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