Chroma 81 - SCART and Colour interface for the ZX81

[siggi]

Looks great

P1070805_800x600.JPG (65.63 KiB) Viewed 4045 times

Siggi

[stefano]

Thank you ! I couldn't get up to here without the Olofsen's help

Do you mind if i borrow the picture for the z88dk website ?

For the record, I've just completed a better gaming device library which permitted me to improve the playability a bit more:

viewtopic.php?f=4&t=552&p=15372#p15372

..is it correct to consider both ZXpand and Chroma-81 having RAM space over the 16K limit ?

[siggi]

Do you mind if i borrow the picture for the z88dk website ?

Feel free to use it ..

..is it correct to consider both ZXpand and Chroma-81 having RAM space over the 16K limit ?

As I understood the documentation of Chroma81, that depends on the setting of the switch for ram @8K(!):
If ram at 8-16K is enabled, it is echoed to high ram ("8K RAM appears in memory map at $2000-$3FFF and echoed at $A000-$BFFF"), which then has priority over external ram behind Chroma, eg. in ZXPAND with ram at 32K-48K enabled. Thus using that memory may also affect the memory at 8K!

Siggi

[stefano]

I put the HRG page just above $8000, is it correct ?

[siggi]

$8000 is OK, if ZXPAND is attached to Chroma81 (Chroma81 does not have ram there).
But if the ram at $2000-3FFF is not used for UDG or other things, I would use this ram, because Chroma81 itself has ram there, if the correspondig switch is set. Thus the program would also run without ZXPAND.

HTH Siggi

[stefano]

I think it is too small for a whole HRG page (6144 bytes).
I'll try to squeeze the code in the lower 16K, the actual code is just too big by few hundreds of bytes..

[siggi]

8Kbyte ram starting at $2000 should be large enough for a 6KB Hires file
Wilf Rigter also used this memory area for most of his HIRES-programs.

Siggi

[stefano]

Good, so..
I updated my "expanded submission". Same link as above, WRX at $2000, Chroma81 and Joystick enabled:

EDIT: file is attached here

Hope everything will work well.

[siggi]

Hi Stefano
meanwhile I found some problems when running the "Chroma-Wall" (where I made the picture): sometimes the screen jumps one line up or one line down or even gets shortly dark . But that occurs only at the LED-TV, which is connected via SCART/Croma, not on an old b/w TV, connected to the RF standard output of the ZX81!

The timing during HIRES seems to be a little bit different compared to LORES display, which seems to affect my LED TV (or Chroma?): it gets out of sync.

But this also occurs, when I run other HIRES software, like Wilf's HRDEMO30 (within the SHREB-package at http://www.pictureviewerpro.com/hosting/zx81/fredn.htm ).

HRDEMO30.P

(13.18 KiB) Downloaded 206 times

.

Does anyboly else notices the same effects using this programs with his Chroma81?

Siggi

[stefano]

Siggi, if you agree I can prepare a test program with a tune option similar to the one we used in the past, perhaps it is only a wrong vsync delay.