> What's the meaning of VR0 & VR1 bits in register 8?
Ok, I'll explain them.
> 0 BW 32 Greylevel MVDPmode out trough CompositeVideo output.
> (Normally composite video and RGB are not generated from this
> output but from another on the MVDP).
Correct.
> 1 SP ? Sprite (0=On, 1=Off)
The name is SPD, not SP. With it you can disable the sprites, which
drastically spees up the VDP (that's why the name is SPeeD).
> 2 VR0 VRAM size and speed
It's the VRAM mode.
According to my docs it has to be 0 (it has no value), but when looking to
the meaning of the 3rd bit I think you can switch between 1 and 4-bit VRAM
with this. On MSX always keep it 0!!!
> 3 VR1 VRAM size and speed
Again, it's the VRAM mode.
My docs tell me:
1 = 64k x 1bit / 64k x 4bit
0 = 16k x 1bit / 16k x 4bit
I don't know what the value on MSX is, I guess it has to be 1 all the time.
You can check the value by doing PRINT RIGHT$("0000000"+BIN$(VDP(8)),8) in
Basic.
> 4 CB colour Bus direction (0=Output, 1=Input)
This one can also have 1 value, otherwise the VDP won't work (it might even
blow up!). Once again, check the default using VDP(8) in basic.
> 5 TP ?Transparent from palette
If this bit is set color 0 isn't transparent anymore. As far as I know this
only affects the sprites. You know the use of it, don't you?
> 6 LCS Lightpen Select (active 1) connected trough colourbus
1=lightpen, 0=no lightpen. Always keep 0 in current MSX configurations.
> 7 MSE Mouse select (active 1) connected trough colourbus
1=Color bus input / Mouse possible
0=Color bus output / No mouse possible
Always keep 0 because the mouse is controlled through the PSG. The name of
this bit is therefor a bit confusing.
~Grauw
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