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

[Ryan Pritchard]

Hmmm,

Further investigation this evening makes me believe that the CoCo is  
fine and that the 64K x 1 chips got a little toasty on the  
desoldering.  I checked all the jumpers, they were all in the correct  
place.  I checked for any scratched traces and found none.  I pressed  
down on every socketed chip.

Now I get the following results, which would support my beliefs.

Color Basic 1.1
PRINT MEM
14631
Same with 64K(32K config) or 16K

Extended Color Basic 1.1
PRINT MEM
8487
Same with 64K(32K config) or 16K

Disk Extended Color Basic 1.1
PRINT MEM
Fails with 64K chips configured as 32K
Gives the following result with 16K reinstalled
6439

Darren A it seems I can either get some 64K x 1 chips from you or I  
deal with Jameco.  Let me know.

Regards,

Ryan Pritchard
Fun Extends All Basic Life Expectancies



On 26-Sep-08, at 3:19 PM, Ryan Pritchard wrote:

> 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