Sinclair ZX80 / ZX81 / Z88 Forums

Hello and welcome Elfish I'd really like to get that thing running for my dad and I read a lot about composite mods. I came across the ZX8-CCD PCB. Anyone knows if the board is also compatible with the board and ULA? The ZX8-CCD is only designed for use with monochrome video, that is, for use with a...

People are following the details that are widely available on the internet, even though those details are slightly misleading.

Mark

It is possible that not all original Ferranti ULA chips would have worked correctly with WRX hires graphics software. Remember, the hardware was not designed for this. With the wide variety of components used (different makes/models/manufacturers of processors, RAM, ROM, the different ULA versions a...

Are you using battery back up? If no, then the 10kΩ resistor between pins 27 and 28 is not needed. Pin 27 will always be driven by the Z80 /WR control line. This is not true however if the RAM is being powered by a backup battery, in which case, the battery supply (pin 28) would need to pull-up pin ...

Translated to English: Hi everyone, I'm new here. I have always had a passion for electronics in general. Taking up my ZX80 I wanted to reconstruct it, I see a lot of information on it online, but I'm not a good programmer. I studied the Z80 35 years ago, I remember little. Thanks to you I discovere...

It's extremely unlikely that TR1 is causing an issue. Transistors in circuits like this are not under any stress whatsoever, and transistors are fairly hardy and reliable devices. I'm sorry that I can't help you much. But with edge cases especially when it comes to timing issues, they can be extreme...

msknight wrote: ↑Fri Mar 08, 2024 1:50 pm In case it matters for the price of fish, here's the clock as going in to the processor...

That is exactly I would expect.

Mark

@Crayon21, in your original program, you are not actually using X to set the print position. You are using J and K. That's why the program appears to ignore the cursor keys. Mark I'll give this a go, thanks I can get left but it goes right when I hit the edge of the screen. is there a corrected rom...

@Crayon21, in your original program, you are not actually using X to set the print position. You are using J and K. That's why the program appears to ignore the cursor keys.

Mark

I assume you are talking about the PRINT AT a,b ? In BASIC in general, only TAB is universally supported. Individual BASIC implementations hence use their own systems. It's just something you have to get used to. If it helps, it's the character position, hence not graphics related. With a character ...