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ZX80-help needed!

Posted: Wed Dec 06, 2017 10:02 pm
by nollkolltroll
I am developing a graphical ZX80-demo, but I only have a Minstrel to test on. Fine as that machine is, I REALLY would like someone to beta-test on a real ZX80 before I release anything to the public. The code requires a ZX80 with 16k RAM expansion and the 8k ZX81 ROM. A 4k ROM version will be made in the future as well.

Also, I was hoping to get the code ZX81 compatible. I need to know how to shut off the HSync completely (unlikely), or synchronize with it, as I generate all the syncs in the code. Everything is 207-cycle exact, but the ZX81 generates HSyncs all over the place...

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 10:32 am
by Shaun_B
Hi,

As I understand it, ZX81 in FAST mode is 1:1 with a ZX80 and an upgraded ROM. At least Paul Farrow's flicker-free games that I've tried work on the ZX81. That would be a good indication that your program works on a ZX80 with an upgraded ROM.

Edit: There will be some differences between the old 8K ROM and the new 8K ROM, which will be documented here.

Thanks,

Shaun.

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 12:23 pm
by nollkolltroll
I really hoped the ZX81 in FAST mode was like a real ZX80, but it is not. The always on HSync generator disturbs my "magic". I will have a look at the flicker-free stuff and see what has been done there.

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 6:19 pm
by nollkolltroll
I got the code working on a ZX81 now. A delayed start and I generate my own HSync at the same time as the ZX81 HW, so it works OK.

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 8:28 pm
by Shaun_B
Excellent :-) - if you can share some snippets / knowledge then this would be good too.

Regards,

Shaun.

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 8:34 pm
by nollkolltroll
The source of the demo will be revealed at release ;)

Since I do all the graphics code without any ROM-routines, it boils down to making sure all routines insert HSync at every multiple of 207 cycles. What I had missed was that the start of the program had to delay for a proper amount before starting my routines, to sync with the HW, which is synced to the ROM-routines. I had also fumbled in the VSync, not being a proper multiple of 207.

Re: ZX80-help needed!

Posted: Thu Dec 07, 2017 9:58 pm
by sirmorris
Awesome work as always, Adam!

Re: ZX80-help needed!

Posted: Sat Dec 23, 2017 10:47 pm
by marste
If you need to test on a standard ZX80 (4k rom) I can volunteer, let me know!
PS: until Dec.25th I'll be able to test probably immediately, else after half of January.

Happy hacking!

Re: ZX80-help needed!

Posted: Sun Dec 24, 2017 8:49 am
by nollkolltroll
All is sorted, thanks for the offer!