ZX80-help needed!

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
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nollkolltroll
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Location: Stockholm, Sweden

ZX80-help needed!

Post by nollkolltroll » Wed Dec 06, 2017 9:02 pm

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...
/Adam

Shaun_B
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Re: ZX80-help needed!

Post by Shaun_B » Thu Dec 07, 2017 9:32 am

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.

nollkolltroll
Posts: 194
Joined: Sat Sep 27, 2014 7:02 pm
Location: Stockholm, Sweden

Re: ZX80-help needed!

Post by nollkolltroll » Thu Dec 07, 2017 11:23 am

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.
/Adam

nollkolltroll
Posts: 194
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Location: Stockholm, Sweden

Re: ZX80-help needed!

Post by nollkolltroll » Thu Dec 07, 2017 5:19 pm

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.
/Adam

Shaun_B
Posts: 334
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Re: ZX80-help needed!

Post by Shaun_B » Thu Dec 07, 2017 7:28 pm

Excellent :-) - if you can share some snippets / knowledge then this would be good too.

Regards,

Shaun.

nollkolltroll
Posts: 194
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Location: Stockholm, Sweden

Re: ZX80-help needed!

Post by nollkolltroll » Thu Dec 07, 2017 7:34 pm

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.
/Adam

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sirmorris
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Re: ZX80-help needed!

Post by sirmorris » Thu Dec 07, 2017 8:58 pm

Awesome work as always, Adam!
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

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