TS1000 Internal RAM: Part 3
13Just about finished working on this TS1000. I had to put a different four-pin header in for the 32KB SRAM board to avoid a screw pillar ... but it fits within the case ... will be the same for the ZX81 case.
Confirmed the 16KB still works from BASIC by creating a 3000-element numeric array that takes about 15KB of RAM.
I also had to remove the switching regulator - the case was just too big - remove the regulator totally so now the machine will run on 5V via my custom USB power cable. A lot less heat, especially with the vLA81 installed!
I tried to load some software via the EAR input (i.e. from tape) by playing a WAV file in Audacity but couldn't get the right volume level ... too high and the machine will reset, too low and it won't register.
Will try again later.
My RAM board:
https://github.com/0ddjob/ZX81/tree/main/RAM_Upgrade
Another design with surface mount SRAM:
https://github.com/redhawk668/ZX81-Internal-16K-Expansion
vLA81 modern ULA replacement:
https://www.vretrodesign.com/products/vla81-zx81-ula-replacement
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