This is a totally useless project; I already have a working machine, some components are very expensive, and hard to purchase some of them.
However it is very exciting! For example the ULA came from the other side of the Earth (form New Zealand), the axial capacitors came form another side of the Earth (form USA), and there are some factory nowadays, which produce the mechanics (PCB, case and keyboard components).
These pictures show the phases of the build.
When I turned on firstly the board then it was not worked of course... The main problem was, that the low level of the ULA clock generator output was too high (0.7V), so the transistor - which got this sign - was always open. My solution is a serial diode with the base resistor (red arrow shows it in the picture). Another problem was the Z80 processor, which is not worked, I do not know why. But with a special processor board - which contains a Z80 processor plus 32kbyte RAM -, the computer started immediately.
The third picture shows the bottom side of the assembled machine. You can see a 4 wire cable, which provides the power supply for the 4116 type RAMs. I made an own panel instead of the RF modulator, which has a video output circuit and the +12V, -5V maker power supply.
I developed a special ROM socket too, which can handle 4 selectable ROM images.
And of course I left out the heater 7805, I put a step down switching unit instead of it.
