Chroma 81 - SCART and Colour interface for the ZX81

[siggi]

Yes, please do so.

Thanks
Siggi

[stefano]

I verified our past experiment and we were biasing the 64 rows mode only.
What the fullscreen mode does is to base its delay onto a line counter in 16424, which is either 55 (european TV) or 31 (USA). I don't think we have a problem here, but you can experiment by poking different values at 16424, if you want to experiment with it.
It is also useful to know if the old WRX programs give problems as well, I'd expect so.

The two test programs I'm attaching slightly shift the picture horizontally to try to make the hardware get a better moment to sync.

[siggi]

Hi Stefano
first I started the LSHIFT-Version and the picture was stable. But after approx. 10 or 15 minutes the problem was there again.
Both LSHIFT and RSHIFT are not giving a stalbe picture, when the system (or CHROMA?) has warmed up!

I don't think, that pokeing MARGIN will help, because it is updated AFAIK on every keyboard-scan.

And there is another problem: the first screen is not readable:

P1070808_800x600.JPG (105.64 KiB) Viewed 4629 times

Siggi

[stefano]

Ok, the startup screen problem is my fault
Could you please test other HR programs and see if it is only the Chroma mode, z88dk in WRX mode, or every WRX implementation giving troubles ?

[siggi]

Here my first results:
OUTLAW.P (Dr. Beep): stable picture, but some stable distortions at the top of screen
SPONZY-ROM: stable picture
Nuclear invaders (NUCINV16): unstable
Microman (full WRX): unstable
Pacman: unstable
HRDEMO30: unstable
DSTAR (old fullscreen WRX-Version without sound): unstable

So most hires programms are not shown stable on my Led-TV/CHROMA81

HTH Siggi

[stefano]

Ok, microman and dstar are based on almost the same WRX implementation (which, in turn is derived from the Matthias Swatosh tool).
Was PacMan a WRX program ?

[siggi]

I downloaded Pacman there:

http://sinclairzxworld.com/viewtopic.ph ... lit=pacman

Maybe it is Pseudio HRG, but I don't know exactly

Siggi

[stefano]

For what I can see on the sources, it is pseudo-hrg.
This probably means that we need the help of the "hardware" team

*edit*
Could you please check if the text mode background is now correct ?

[siggi]

On the first start of the game the background of the initial screen is white (OK)
After end of the game the initial screen is shown again. Then it is again not readable (FAIL)

HTH Siggi

[siggi]

Latest News:
I testet (played) the latest "wall-expanded.p" with an old color CRT(!) with SCART input:
the picture is stable after more than 1 hour

So there are the questions:
Is it an issue of my "modern" LED-TV??? (despite the SPONZYROM-display is stable?)
Am I the only one who ist playing around with Chroma81 and real hardware? Does no one other can report about his experience?

Siggi