This was the quickest way of getting a known-good reference machine.

Alas it is not very hackable, because most of the logic is inside the ULA.

It did come cased with a working membrane keyboard.

I extended the connections to the keyboard using extra-flex wire, allowing operation with the PCB accessible without removing the membrane from the case. 

I hacked the ROM socket to accept a modern flash ROM, so that I could experiment with modified firmware. 

I removed the 5V regulator and heatsink then wired a 2.1 mm power socket so that could be powered by a common 5V wall-wart power supply.

Attached is the G007 graphics board. I have tried to reduce the RAM-pack wobble by fitting a 32K RAM chip over the G007 ROM chip. D7 and D6 have to go to the edge connector. This should be an easy hack but for some reason it didn't work and I left that hack in that state. It still works with an external RAM pack if the 32K RAM is removed.

2023-09-15

Not working right now, I checked the ROM and RAM address lines. I tied the ROM /WE pin high. Seemed not to work but I had set my TV for white-on-black for my ZX80. Adjusting the controls allowed the ZX81 signal to be seen.

Still not working with the G007, or the DRAM pack, or both.