Sinclair ZX80 / ZX81 / Z88 Forums

Welcome back Thommy! I've actually been keeping an eye on your most impressive work for a long while now. I'm often found over at *. and seeing as I like my emulators minimal and potentially seizure-inducing - well there was only one choice really. As a Mac owner I've built from source a few times ...

Hi all. I wrote a ZX80/81 emulator back in 2011 , of which I am sure any recollection has long ago fallen by the wayside. If you recall it at all, it might be as the emulator that burnt your CPU by simulating and propagating every single bus transition, or it might be because it was a good OS X-cent...

I know that, but this is used only/mainly for compatibility to old components. New developments for PC's should neither use parallel nor serial interface. This is quite old stuff and by the way to slow in general (not for ZX81 :P ) and no more state of the art. The only advantage is that these inte...

In my emulator, I have a function that hooks itself up to trigger on IOREQ and WR low. In that I grab the value of the 16 address lines and I added the following quick snippet: if(((address&0xff) != 0xff) && ((address&0xff) != 0xfe) && ((address&0xff) != 0xfd)) { printf("write to %04x\n", address); ...

I'm not a Windows user so I can be of limited help only, but I can point you to http://www.microwave.gr/giannopk/zxcomp ... _v0_04.zip for a Windows tool to convert from .P or .O to .WAV, which will get you to the sound card.

Very simple: with the standard ZX81 I/O ports confined to a small number of I/O addresses, you can use the remaining I/O addresses in any way you like, with 0 worries about affecting the ULA's circuitry (NMI's on/off, Vsync etc). I guess that is justification, but the contrary argument is that you'...

What sort of incompatibilities are we talking about? While testing my emulator I've not yet found anything that makes assumptions that would break with your suggested 32kb RAM scheme, presumably because some of the 64kb boards have a similar effect. As for port IO, is there any justification for a c...

Just a quick update on this: as I now have Internet access in my home, I've moved the project to public hosting at https://github.com/TomHarte/Clock-Signal. It's still nowhere near ready for public consumption but a normal end-user website will be forthcoming.

Dumb question, probably, but in my emulator (which is being structured so that many of the same considerations apply) I've completely ignored the clock and I have the relevant video stuff set up so that it is triggered on A15 high, M1 and D6 low. It then grabs whatever is on the data bus and starts ...

Directly on "is introducing half a cycle of latency in all communications problematic?" and my concerns about cumulative latency, some datasheets — including the one I'd followed — show the refresh signal going active on the trailing pulse of T3. Supposing that were true, the ULA would spot that ref...