Sinclair ZX80 / ZX81 / Z88 Forums

If you have a 16k RAM-pack, make it HRG-compatible. Simple enough, and very cheap.
Lacking a RAM-pack, build it internally. Trick out the ZX81 with 32k in the 16-48k range (HRG compatible) and 8k in the 8-16k area (make it UDG compatible). This will allow you to run most programs.

Haha, yes, the CPLD ULA is available. But this is not the "dreaming-and-I-will probably-do-it" thread, it's more like a "what-is-possible-but-not-until-I-have-oodles-of-time" thread. SO: I won't be building that any time soon. But: a big hooray to RetroTechie for publishing such a fine project with ...

That sounds very good, I'll have to look into my priorities regarding my ZX81 projects. First create the project-list...

and dreaming some more, it would have been very nice to have a 4MHz clock with a 256 T-state raster counter for that exact 15625Hz raster. Easier to do the raster calculations, and more CPU-power running the real program. I think it would not require that much changes to the ROM, and with an FPGA/CP...

Now that I've ordered the ZXpand I started thinking. Would it be possible to use any of the (presumably available) serial ports on the PIC to talk to a PC in order to save/load progs to the SD-card? Would make it so much easier and faster to test code on the real thing.

...what a change it would have been if the ZX81 would have been released with 8k RAM and UDG enabled. Placing it in the 8-16k area would have made it possible to really expand the memory with 16k additional RAM! It makes sense compared to the ZX80... But I guess RAM was too expensive. Oh well. Time ...

Well, it was finally time. My second ZX81 got a composite video output. Now I can finally connect both my zeddies to the videocard in my Linux-box. No need to drag out the 5" TV every time.

I clicked on the ZXpand, AY-module and keyboard. Now awaiting invoice. WOHOO!!!

I just downloaded the binaries, now it's only a matter of getting going...

I'd really like to test coding in C for the Z80, but so far I've resisted. Must encourage myself better.