Sinclair ZX80 / ZX81 / Z88 Forums

stevenmcdonald wrote: ↑Sat May 11, 2024 1:22 am It blows. my mind that it's highly likely that nobody in the world thought to do this in the 43 years since this computer has been released!

And technically this technique would work on the ZX80 also, and so that's 44 years that no one else has thought of this!

You are indeed correct. But if you only wanted to display one row of characters then you'd save a byte at least. Or if you wanted to display multiple rows and your program could tolerate having a non-uniform row length then you could start each row with LD H,D / LD L,E:

It's a very interesting new technique. As an optimisation, you can replace the two instructions LD H,D and LD L,E with single instruction EX DE,HL to achieve the same effect but using 1 less byte per row.

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?