Sinclair ZX80 / ZX81 / Z88 Forums

Congratulations! Regarding the Memotech HRG, I bought one and remember being thoroughly disappointed. It came with a set of ROM routines for plotting, drawing lines, etc, but they were so hopelessly, orders of magnitude slow that it was clear that there was no use for them at all. I was a machine co...

Hello Becky, welcome to the forum!

(Sorry, I don't know the answer to your question though).

Okay thanks. It's not a big deal really, it would just be nice to be able to comment out a block of code so I can see more easily how many bytes I've used

I was looking at the photographs trying to understand the fabrication process; then I realised that they're made of awesome!

You can tell this isn't real Sinclair tech. If it was, it'd take six months to arrive, half the chips would be repurposed rejects, and there'd be an extra ROM bodged into the back on a dongle

PokeMon, a question.

Is there any way to comment out blocks of code simply (that is, multiple lines) rather than one line at a time? I'd like to do it while testing alternate subroutines, etc, but I can't seem to find a way

Strange, I'm not doing any calls to ROM. Still, it crashes if HL' is changed. It appears to be okay to use BC' though. So far

Ah okay, that makes sense. It's just a normal RAND USR 16514 type thing, but I guess that decoding the address from the program line uses the FP calculator.

I won't be using BASIC in the finished program, but it's quite handy to have it working for testing

This sort of reminded me of the lighting control board we had in the theatre I worked at in the 1980s. It was a Strand Compact 120, very old tech by today's standards- it even had magnetic core memory(!)- and in general the service engineers, faced with an inexplicable glitch, would put something li...

Hopefully a simple question for the experts here- It seems changing the value in the hl' (alternate) register pair causes the ZX81 to crash. I thought the prime registers were safe to use, except af' which is used by the screen display routines. Is hl' used, what for, and is there a particular value...