[Coco] CoCo 1 upgrade from 32k to 64k - Help

[Bruce W. Calkins]

E-variant CoCo 1s needed a 74LS02 chip legs bent up and wired in to 
enable 64k.  Look for the PDF "Tandy's Little Wonder" for instructions.  
E-boards had a jumper for high or low side use of the 64k chips.  The 
assumption was that half good chips would be sorted out and sold cheaper 
than all good 64k chips.  I've never seen any half good chips.

Bruce W.



On 05/01/2017 06:50 PM, Glen Hewlett wrote:
> Hi All,
>
> At the CoCo Fest I won an auction for an original CoCo 1 that was identical to first CoCo I ever owned.  It currently has 32k and it looks like it was a Radio shack upgrade since it also has the 32k badge on top.  I was testing to see if it was actually a 64k CoCo but when I ran the program to copy the ROMs to RAM and leave it in all RAM mode the program runs but I still can’t change any bytes where the ROMs are loaded.  So it still seems to be setup in hardware as a 32k CoCo.  One weird thing though is that if I do a Poke &HFFDF,0 it locks up the computer.  But If I try the same Poke &HFFDF,0 after running the program that copies the ROMS to RAM the computer doesn’t lock up but again I can’t change any byte above $8000.  I also tried the 64k game SailorMan and it fails to start.  I’m pretty sure it’s not a 64k CoCo 1.
>
> I found a old site that was found in the internet archive the site was called Paul D's CoCo Hardware Page
> http://www.oocities.org/theother_bob/PaulDpages/hardware.html <http://www.oocities.org/theother_bob/PaulDpages/hardware.html>
>
> It gives details about upgrading a Model E board CoCo 1 to 32k which I’ve followed and it looks like it’s already done on my Model E board.  At the end of the article it says:
>
> "You should have 32K. For the 64K mod of this board, e-mail me to request it.”
>
> Does anyone have the instructions for modifying a Model E board 32k CoCo 1 to 64k?
>
> Any help is appreciated,
> Glen
>