I checked your overscan-proggie and it indeed looks very, very nice.
> NB: The display adjustment trick DOES NOT WORK since display start is only
> checked ONCE per frame by the vertical blanking circuitry. You can only
> alter horizontal adjustment on the fly (the register is checked every
> raster line).
Fortunately, 'cause otherwise my nice 4-direction smooth scroll (which still
isn't perfect!) wouldn't have worked.
> I've noticed rare sprite behavior when using graphics 7 (SCREEN 8) mode 2
> sprites.
>
> 1) It's impossible to obtain opaque black (color code 0000 + active pixel
> on the pattern).
True. You'll have to (re)set bit 5 in VDP r#8 (something like "Transparant
mode enable").
> 2) "Bright" black (color code 1000) yields *ORANGE* (!!!).
Color code 1000??? What do you mean with 1000??? Is it an RGB-code (which
should then be 3-digit, not 4-digit), or is is a binary number (then state %
or &b in front of it)???
If it's binary then it's color code 8, and if I do COLOR 15,8 in Basic I get
a red background.
> Attached is a tiny test. It shows 2 horizontal orange blocks when in
theory
> it should be a solid opaque black square with two "bright" black strips.
> I've tested it only on 9938 VDPs.
>
> I'd appreciate if someone could test the program on later VDPs so I could
> make the assumption it works this way on all MSX models.
On my v9938 VDP I saw a bright 2x2 green dot.
On my v9958 too.
By the way, this file only worked in Dos1-environment... Why??? Are you
changing the memory or so??? Also (and that also goes for the
overscan-demo), your programs reset afterwards... is it so difficult to
execute a BIOS-call to select screen 0 again and the terminate the
Dos-program (JP 0 or LD C,0:CALL 5)???
Errm... Something completely different... I checked the Yamaha-site, and at
the videoprocessor-part I read the following:
Product: V9938
Display Type: CRT
Display Format: Up to 512x424
Grayscale & Colors: Up to 512
Output: Linear RGB & Composite Video
Up to 512 colors???
How did they think to do that??? I hope not using screensplits...
And about the greyscale-bit... if I set the bit in one of the VDP's
control-registers (0, 1, 8, 9) my screen does everything but turn grey.
~Grauw
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