Heavily Customised USA ZX81: Part 3
46Continuing on with this lovingly customised USA ZX81, I finally replace the original 7805 linear regulator with a modern switching version (a PSU2 from www.ezsbc.com).
Then, obviously, I need to see if the machine actually works so I replace the RF modulator can contents with a simple emitter follower buffer as described below:
https://www.bytedelight.com/?page_id=3560
I was also able to try out the keyboard - very nicely implemented. It seems nice to type on.
Now that I can see it's working with its original 2Kbyte of RAM, next it will be time to test the original 16Kbyte expansion board. It's a little impractical for today, but it would be good to verify if it still works at least. For a modern solution, I could either replace the 2Kbyte of internal RAM with 32Kbyte, or rely on a future owner using a ZXpand which comes with its own RAM expansion (so no need for internal changes).
Part 1: https://youtu.be/afQWRdUCyVE
Part 2: https://youtu.be/tdTu4gKl1bc
Part 3: https://youtu.be/vqhR0q9qCmo
#TS1000 #ZX81