Wow - this is amazing. I was gifted a ZX81, as my Dad bought me a ZX Spectrum, which I let go a couple of years ago, because I did not have the time to repair it. I'm still very disappointed in doing that, as now I want it back and its very hard to source one. I will definitely dig out the ZX81 and start working towards getting it up and running and modified as per your videos. In this way, I can re-learn all my electronics background I studied, before switching to IT in my career.
A real keyboard greatly enhances the ZX81. The conundrum of repairing modding enhancing a ZX is why bother, emulation can run most ZX softwsre. A CP/M machine would be a better computer to play with hardware and more serious software. If doing ZX stuff , keep one stock as a collectors displsy item, source a second mod machine.
Keep a look out for a Cidco Mailstation at thrift stores or garage sales, a useful battery Z80 machine, tney have nice potetial donor keyboards for ZX machines.
I built my ZX81 in December 1981. The kit came with sockets for all ICs and had resistor nets. This doesn't have sockets or resistor nets. That it doesn't have sockets probably means it was sold ready built, but it is still strange it doesn't have resistor nets. I believe I could not replace the resistor nets with resistors in an easy way, because the board assumed resistor nets. What issue of board is this? I broke one of the resistor nets when I built mine, but then I built a resistor net of single resistors. The reason I broke the resistor net was that I mounted it in the wrong direction and it was when I desoldered it that I broke it. I didn't have a desoldering pump because I didn't know they existed. Anyway, I got my ZX81 working in 1981 and it still works.
Great video series! I'm restoring a ZX81, and it helps a lot. Could you tell me what is the reference of the DC-DC converter replacing the 7805? Or, at least, which word to use to find one on ebay or so? Thanks!
The NOP trick is clever, but it's also exploiting an instruction set quirk: NOP is 0x00 on the Z80. It'd be harder to pull off this kind of trick with, say, a 6502.
Wow - this is amazing. I was gifted a ZX81, as my Dad bought me a ZX Spectrum, which I let go a couple of years ago, because I did not have the time to repair it. I'm still very disappointed in doing that, as now I want it back and its very hard to source one. I will definitely dig out the ZX81 and start working towards getting it up and running and modified as per your videos. In this way, I can re-learn all my electronics background I studied, before switching to IT in my career.
Glad to hear it!
A real keyboard greatly enhances the ZX81.
The conundrum of repairing modding enhancing a ZX is why bother, emulation can run most ZX softwsre.
A CP/M machine would be a better computer to play with hardware and more serious software.
If doing ZX stuff , keep one stock as a collectors displsy item, source a second mod machine.
Keep a look out for a Cidco Mailstation at thrift stores or garage sales, a useful battery Z80 machine, tney have nice potetial donor keyboards for ZX machines.
I built my ZX81 in December 1981. The kit came with sockets for all ICs and had resistor nets. This doesn't have sockets or resistor nets. That it doesn't have sockets probably means it was sold ready built, but it is still strange it doesn't have resistor nets. I believe I could not replace the resistor nets with resistors in an easy way, because the board assumed resistor nets. What issue of board is this? I broke one of the resistor nets when I built mine, but then I built a resistor net of single resistors. The reason I broke the resistor net was that I mounted it in the wrong direction and it was when I desoldered it that I broke it. I didn't have a desoldering pump because I didn't know they existed. Anyway, I got my ZX81 working in 1981 and it still works.
Great video series! I'm restoring a ZX81, and it helps a lot.
Could you tell me what is the reference of the DC-DC converter replacing the 7805? Or, at least, which word to use to find one on ebay or so?
Thanks!
Thanks! The DC-DC converter is a Traco Power TSR 1-2450.
@@thebyteattic Thank you very much!
Do you have a part number for that DC to DC converter and the tape connector sockets? Thank you.
I use the TracoPower TSR1-2450 for 5V DC output: www.tracopower.com/int/model/tsr-1-2450
@@thebyteattic Thank you very much. I'm really liking your repair videos. 👍
You know why it is called a CURSOR, because when things go wrong you don't want to whisper sweet things to your computer.
:-)
The NOP trick is clever, but it's also exploiting an instruction set quirk: NOP is 0x00 on the Z80. It'd be harder to pull off this kind of trick with, say, a 6502.