GFX9000 / v9990

By MarMSX

Resident (40)

08-09-2008, 03:49

Hi.

I'm experiencing some troubles with gfx9000 (emulated on OpenMSX), using GBASIC.

The GBASIC manual says that we can set the image space, according to the command GSET IMAGE = ???

In the manual, the layout shows that each page has 256 lines (even only 212 can be shown).Hi.

I'm experiencing some troubles with gfx9000 (emulated on OpenMSX), using GBASIC.

The GBASIC manual says that we can set the image space, according to the command GSET IMAGE = ???

In the manual, the layout shows that each page has 256 lines (even only 212 can be shown). That's ok.

But if you try to create a image using the whole space (for GSCREEN 13, IMAGE = 512), which says that we have a full image of 512 x 1024 pixels, the last lines seems to invade a 'reserved area', causing some problems.

The question is: is there a reserved area in GVRAM for GBASIC?

Thanks.

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By AuroraMSX

Paragon (1902)

23-09-2008, 12:43

I'm not familiar with GBASIC, so I can't really tell to which display mode this SCREEN 13/IMAGE 512 corresponds and without more specifics about those 'problems' it's hard to tell what exactly goes wrong. I think there are basically two possibilities:

Assuming that this SCREEN 13 corresponds to mode B3 (512x212 display area) in 8bpp, then your 512x1024 image will fill all of the Gfx9000's VRAM. However, a bit of VRAM is (indeed) reserved for the hardware cursor (#7FE00~#7FFFF), which might account for your problems. In that case set bit 6 of register R#8 to 0 to disable the cursor.
Not entirely unthinkable: Gfx9000 emulation in openMSX is b0rked. Did you try your program on a real MSX with a real Gfx9000?

By nerlaska

Master (166)

23-09-2008, 15:26

Gfx9000 emulation in OpenMSX is far from perfect. Some screenmodes don't work correctly and some writes to some registers don't work in the same way than in a true V9990

By AuroraMSX

Paragon (1902)

23-09-2008, 15:55

Gfx9000 emulation in OpenMSX is far from perfect. Some screenmodes don't work correctly and some writes to some registers don't work in the same way than in a true V9990Then please file bug reports! Bugs don't go away by themselves, only when people report them, it is possible to track down the problems and fix them! Or talk to the developers directly on IRC (freenode/#openmsx) ...

By Manuel

Ascended (19465)

23-09-2008, 23:32

Shortcut to IRC: http://openmsx.sf.net/mibbit.php

For the rest: as AuroraMSX says. When we don't get bug reports, we won't fix it, unless we accidentally stumble upon things ourselves. And that chance is really really small. Don't think someone else already did, that chance is also quite small :) Just let us know about any bugs in emulation, please!

By RyJuZo

Master (236)

24-09-2008, 01:20

Aurora is right on the money...

you are filling the entire vram of the gfx9k with an imagesize of 512x1024 in screen 13. I recommend using slightly less lines. otherwise disable the cursor.

so in this case nothing wrong with the emulation of openmsx.

on a side note:

There are a lot people uttering that the emulation of the gfx9k on openmsx is *FAR* from perfect.
I think this is being overdramatized a bit. Yes there might be some area's where the emulation is not perfect but you won't find them so easily...
I've been experimenting(extensively) for while now with the gfx9k in combination with openmsx. I haven't met any problems YET ! Other than that the emulation is slower.

If you suspect a bug try it on real hardware first in most cases you'll find it's in your own code not the emulation.

By nerlaska

Master (166)

24-09-2008, 08:25

well .. i didn't try to say nothing bad of the OpenMSX emulator. Is a good emulator and i work with it with the GFX9000 emulation.
and with respect <is far from perfect>, well .. may be is a bit overdramatized like says RyJuZo but i have found some emulation problems, mainly that you can code something that works in the emulator but not in the real machine and i think (i need to test depthly) that some screenmods doesn't work correctly in the emulator.
In any case, sorry for my comments about OpenMSX emulation.

By AuroraMSX

Paragon (1902)

24-09-2008, 12:06

i think (i need to test depthly) that some screenmods doesn't work correctly in the emulator.
In any case, sorry for my comments about OpenMSX emulation.No need to be sorry, at all But please do tell what exactly you think is wrong with the emulation, so that it can be fixed.