Vintage computer Sinclair ZX81 bringing back to life PACMAN

Some notes:
Wanted to preserve the original keyboard but it was so fragile that the flat cable broke. Bought new one. recent manufacture
When switched on it produced video output (RF) but when pressing different keys it produced gibberish on screen. Consulted different forums and decided it was the Ferranti input output chip (ULA). There as clock signal to CPU and CPU / Memory were producing waveform on data and address pins. Went for vLA81 modern replacement. It worked
As I changed to vLA81 I decided to upgrade memory. It is very easy to do.
Remove old 1k memory. Install socket 24 pin. And the you have varies chemises. Consult vLA documentation
Before I replaced the ULA I made video board. Have composite video instead of RF. With vLA81 you don't need that board. As the chip has option to output composite video as well.
Replaced the linear regulator with switch mode. Brought down current from about 470 mA to about 200 mA.
Very nice project overall
Memory datasheets, switch mode power supply and PCB composite video link board on Google drive:
https://drive.google.com/drive/folder...