MZ-700 demos

Is there such a thing as an MZ demoscene?
hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Sun May 31, 2020 11:35 am

The original emulator doesn't emulate correctly the BLNK as I already told on an earlier post.

|/HBLNK| = 64.05603 µs - 36.088 µs = 27.96803 µs -- PHIOx|/HBLNK|--> 99,19910640625‬ cycles
|BLNK| = |/HBLNK| - 2.16508 µs = 25.80295 µs -- PHIOx|BLNK|--> 91,51983828125 cycles

The emulator does |/HBLNK| == |BLNK|. I'm not sure how to correct that because the emulator starts |BLNK| = 0 at the same time as |/HBLNK| = 1 whereas it should be |BLNK| = 1 at the same time as |/HBLNK| = 0. And I see no easy way to do so with its current implementation of events.

I don't know the exact sequence you use : there are two requirements to obseve, the PUSH sequence must be under 91 cycles, and the update raster should be under 227 cycles. If you miss one requirement, you screw up the graphics drawing.

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Sun May 31, 2020 12:01 pm

Et sinon, je vois un début prometteur sur ta photo puis ça se gâte à la deuxième ou troisième ligne de caractères.

The timings appear a little off after several raster updates so the issue is probably the length in cycles of your raster code which is two close to the end of the raster and makes the next raster to miss the BLNK synchronization at one moment: after that you only will get characters displayed.

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Sun May 31, 2020 12:50 pm

I tried two ways through my Unicard.

VGA output from Unicard: the timings is totally off. Just plain characters. It looks like the VGA output of Unicard is a no-go for games/demos using display precise timings.

SCART output from MZ-700: there is a rough mix of characters at the first lines, mostly like yours indeed. Ok the first lines are not exactly the same ones as expected as in my previous post.
sel-euh-jupe-y-terre.jpg

MooZ
Posts: 36
Joined: Thu Mar 01, 2018 9:39 am

Re: MZ-700 demos

Post by MooZ » Sun May 31, 2020 3:04 pm

This one works (at least on my machine...), but fails every 2 frames on the emulator.
Attachments
112.zip
(17 KiB) Downloaded 15 times

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Sun May 31, 2020 4:48 pm

The most important thing is it works on the real machine. It does work on mine. I will try to understand why it fails on the emulator. And thank you for your efforts and your source!

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Sun May 31, 2020 9:55 pm

What I discovered:

1) Genuine MZ-700:

- /HSY[NC] starts the next line.
- /HBL[AN]K goes LOW 9µs BEFORE /HSY going LOW, and HIGH AFTER 28µs.
- BL[A]NK (connected to Z80 /WAIT) goes HIGH 2µs BEFORE /HBLK going LOW, and LOW AFTER 26µs.

-/[V]SYN[C] starts the next frame.
- /VBL[AN]K goes LOW 4ms BEFORE /SYN going LOW, and HIGH AFTER 7ms.

2) EmuZ-700:

- /HSY[NC] starts the next line.
- /HBL[AN]K goes LOW 28µs BEFORE /HSY going LOW, and HIGH WHEN /HSY going HIGH.
- BL[A]NK (connected to Z80 /BUSRQ!?) is doing the same as /HBLK as an inverted signal.

-/[V]SYN[C] starts the next frame WHEN line number is 240.
- /VBL[AN]K goes LOW WHEN line number >= 200, and HIGH WHEN line number is < 200.

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Mon Jun 01, 2020 5:25 pm

So if I change the number of displayed character lines from 25 to 19 (removing 6 lines), I get a stable image. Above 19, I get an unstable image.
2020-06-01_19-16-19.png
2020-06-01_19-16-19.png (8.94 KiB) Viewed 250 times

hlide
Posts: 403
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-700 demos

Post by hlide » Mon Jun 01, 2020 7:44 pm

At least it works with mz800emu from Chaky :
mz800emu-112.jpg

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