Jun-Sung Kim wrote:
> I'm making a pattern editor for GFX9000 now and so I have
> a question.
>
> Do commands(LMMM, CMMM, etc. ) work in P1 and P2 mode of
> GFX9000?
>
> It seems not... or I missed something.
Theoretically they do work. But you'll have to set the correct writemask
bits
in R#46 and R#47. See page 53 of the V9990 E-VDP-III application
manual. It says:
In P1 mode, writing is prohibited on the side not specified as the
transfer destination. Screen A R#46, Screen B#47.
However, I found that some problems do arise when you use commands
containing linear adresses
in the Pattern Nametable Area (A:7C000-7DFFF, B:7E000-7FFFF in P1,
and in P2 from the undifined area 78000-7BDFF, the SPAT 7BE00-7BFFF
and the PNT 7C000-7FFFF).
As long as you do not access those areas all should work fine with
commands not containing linear adresses.
In case of LMMM for example the linear address location is converted to
x,y coordinates. Don't forget to set the correct number of dots
in the x-direction of images space! For instance if it is 256 in P1
you can see the whole vram map as 16 screen 5 pictures on top of each
other. The top one starts at (0,0) = topleft, the next one at (0,256)
etc.. For P2 set it to 512.
Anyway, it works this way with a 'normal' copy LMMM.
But when I use the same system when using commands with linear
adresses, I can't get the BMLL command to function properly
on the addresses described above. And the only thing it wants are high,
middle and low bytes for source and destination...
Weird....
I even wrote a vram monitor for the v9938, swept the whole gfx-VRAM
clean, excuted a BMLL command which copied a blok of FF's,
and tried to find where it went when I executed the command.
The results were shocking! Nothing went to the place I wanted it to.
I don't no if there's some system for
calculating the right address it has to go to, but I need that copy
to quickly rebuild level-screens from VRAM to VRAM. From RAM to
VRAM is too slow on on MSX-2 7 mhz...
Gerald
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