Problem with Scroller Demo ZX Spectrum 128

[frx]

Hi everyone.

I have a problem with the Scroller demo on the ZX Spectrum 128. The demo starts but there is no full cycle synchronization between the ULA and the Z80 processor.

Has anyone run this demo without the artifacts?

[bricabrac]

Sure I do and it works flawlesly. It is not for Spectrum128 but for russian clone Pentagon 128. It slightly differs from standard 128 in terms of timings and that causes those artifacts when you try to run it on 128.

To run it under Spectrum core you have to press F5 to switch into Pentagon 128 and then load it as usual. I was only using disk version (trd) so cannot tell if tap works well to but I expect it should.

[frx]

I tried many options, the same effect, artifacts

[bricabrac]

Sorry, my bad. It should be Alt+F5 instead of just F5. I am getting old :/

Anyways, Alt+F5 will set core into Pentago 128K mode and with that you should be good. But really LCD screen is not the way to watch 8bit demoscene. Especially this one which has gigascreen effect which by definition is dependent on displaying 2 alternate images as the CRT screen is being refreshed. Pentagon video refresh is 48.8Hz and that does not work well with 60Hz LCD panels.

With "pure-scroller" you should be good because it is just an infinite scroll with no text and music, but it still won't look as good as on CRT TV/monitor.

On a side note, those instructions are worth a read: https://github.com/MiSTer-devel/ZX-Spectrum_MISTer

[frx]

I tried many options, with Alt+F5 also. I think LCD@60Hz is the problem. My settings in MiSTer.ini are
video_mode_ntsc=1920,128,208,336,1200,1,3,38,193160
video_mode_pal=1920,128,208,336,1200,1,3,38,193160
I tried swich video timings on TV to 50Hz also. No to good result. I'll try different settings. If I succeed, I'll will let know.
Thanx for Your help.
BTW mister_video_modes.ini You can find below
https://github.com/glopgar/MISTer_video ... _modes.ini
Autor the Scroller demo say: "Vertical 50 fps full screen multicolor scroller for ZX spectrum (Pentagon)."
https://github.com/vasilenkoroman/zx_scroll

[frx]

Hi Everybody again.
I solved a problem with bad color map synchronization in the SCROLLER demo.
The remedy change an entry in the MiSTer.ini file to:

Code: Select all

refresh_min = 50
refresh_max = 60

By selecting the Pentagram mode, MiSTer generated a video frequency that my monitor did not support (only 50 and 60Hz), and by selecting other options of ULA, the colors were bad.
Now the SCROLLER demo works perfectly on ZX Spectrum and ZX Spectrum Next.
MiSTer is GREAT: D