Sinclair ZX80 / ZX81 / Z88 Forums

While testing the new driver I noticed that DSTAR crashes in 192 rows mode unless I add at least one NOP instruction. I'm not sure whether the crash is caused by a memory alignment problem or timing/sync issues, other programs run smoothly on EO. Can you share the program with and without the NOP a...

could anybody see if it fixes the problem ? The program now displays ok in EightyOne but still has issues that my new display driver resolves. Here is the output from EightyOne: NewHangman.png The VSync pulse starts and ends about 2/3rds of the way across a scanline and this upsets the output from ...

I tried to compare it with the Paul's one but it's tricky ! Yeah, it would be as I completely rewrote it from scratch. Paul, do you have an old version of the same driver to understand how it evolved ? Sure, below is the ARX display driver that Andy originally posted on his now defunct website. 15/...

Well, today is the 2nd of April. And for those of us that don't have a ZX8-CCB fitted then a software mechanism that can output the border black will just have to do.

Doesn't time fly? It's the beginning of April already! What better than to start off the first day of the new month with an interesting development. Have you ever played a ZX81 game that is set on a black background but felt that the look of it was somewhat let down by the border having to remain wh...

I have tried the demo on Andy's UDG4ZXpand board on an issue one ZX81 with an issue three ZXpand and got the following results. Thanks. It is nice to know ARX can work with the UDG4ZXpand board, at least in 64 character mode, and therefore there is a base of hardware out there that can run ARX soft...

I recall there was an UDG4ZXpand board (which I think Andy created also but correct me if I am wrong). I'm wondering if this will make the 8K-16K RAM provide by the ZXpand ARX compatible. Does anyone know?

Moggy wrote: ↑Mon Mar 18, 2024 11:57 am Works with SZ-81 ok.

Thanks, good to know. I used EightyOne to get perfect timing in the display driver but there is of course a chance its emulation is still not 100% accurate. So it is good if other emulators that have been written independently agree with the results from EightyOne.

Hmm, I don't think so... as ARX is based on UDG, it is necessary that the RAM address lines A0~A8 are generated by the ULA, which is not the case with memory expansions connected to the rear expansion bus. Yes, good point! :oops: If I had a 64K RAM pack then this would have been obvious during my t...

Here is the source code for the new ARX display driver and demo program, along with the demo program .p file: