[Coco] CoCo 1 64K upgrade failed :(.

[Ryan Pritchard]

I got to thinking this afternoon that there should be nothing preventing me
from taking 41256 chips and merely grounding out pin 1 (A8) to keep the
signal LOW (or is it HIGH? I don't remember my electronics logic that well)
to allow me to use the chips to provide access to the 64K using the A0
through A7 lines with the state of A8 always locked.  A0 - A7 on the DRAM is
MA0 - MA7 according to CoCo Technical Manual.

I wonder if I have an old 8 chip 256K VGA video card kicking around.

On Thu, Sep 25, 2008 at 9:08 PM, Ryan Pritchard <coconut at pritchard.ca>wrote:

> Hi all,
>
> I followed the instructions for the 32K / 64K upgrade that I was provided.
>  I compared all 3 to 4 versions including a 32K only one.  The nice part was
> the 32K only upgrade was the same steps for the 64K upgrade sans some extra
> jumper wires.
>
> I only got as far as having desoldered my 64K x 1 DRAM from my extra Apple
> //e 80 Column Card, and following the steps up to the end of the 32K upgrade
> instructions.
>
> The CoCo does not boot.  I have cut all eight of the correct capacitors
> C31, C35, C45, C48, C61, C64, C67, C70, moved all the jumpers to the 32K
> setting, and tried both the LOW and the HIGH back jumper positions.
>
> I think I may have burnt out the 64K x 1 DRAMs.  I don't know what else it
> could be and since I removed all eight caps breaking a couple in the process
> I can't return to the 16K system :(.
>
> I guess my options are find a good set of 64K x 1 DRAM, or cut my losses
> and pick up a CoCo 3 from Cloud 9.
>
> Currently kinda frustrating because the Extended Color Basic ROM I got
> confirmed the FDC works.
>
> Regards,
>
> Ryan Pritchard
> Fun Extends All Basic Life Expectancies
>
>
>
>


-- 
Regards,

Ryan Pritchard
Fun Extends All Basic Life Expectancies