Raven. A homemade Atari-like computer

[agranlund]

Blitter accelerated fill-rects on the Cirrus Logic:
GEM is using those quite a bit and in Gembench it'll show up on the score for those GEM tests.

IMG_5134.jpg

WDC cards are capable of the same so it will get an implementation too at some point too.
I'd be surprised if fill isn't supported by all or most cards with blitter.

[PhilC]

@agranlund I got as far as reading some of the datasheet yesterday :lol:

Great results, especially when you think how long we've only had the original Nova drivers and very limited card choice.

Thank you :dualthumbup:

[agranlund]

Thanks @PhilC , this is super fun :)
A nice side effect of this graphics driver excursion is that it makes it a bit more realistic to put a VL bus slot on some future version of the board (but certainly not the next A2 revision)


I think the datasheet for Cirrus, as well as WDC, are a lot easier to follow than that of the ET4000.
Still confusing, but at least not quite as bad.

"vgadoc" is quite nice too for getting condensed chipset specific information on a bunch of cards.

[PhilC]

So very tempted

https://github.com/Leshak-pcb/Pine-CL-GD5434

Edit:

Also looking atthe GD542# datasheet and all the chips seem to share the same footprint. Wondering if I chip transplant could upgrade a lower spec card? 5439 chips are listed on eBay, whereas 5434 would need to have a donor card.

[agranlund]

Oh nice! Didn't know there was an opensource GD5436 card.
Interesting idea about transplating a 29 to a 26 card. I wonder if that would work.
Might want to double check the datasheet in case it uses any additional or different configuration pins during reset.

[agranlund]

And the Western Digital WD90C31 can do pattern-filled hardware rectangles too:

IMG_5135.jpg

I've sent the latest work in progress code to Github and attached the updated binary.
Will try to make a proper release zip this weekend.

emulator.prg.zip

The driver has varying degrees of SVGA support for these:
CirrusLogic: GD5401-GD5434, WDC: WD90C31, OAK: OTI67/77/87

And the others should work with standard VGA resolutions.

[PhilC]

Cool, thanks for the update.

I'll probably get a couple of GD5429s and will try transplanting one on my 5422 card at some point as I'm not likely to use that card otherwise.

[agranlund]

If I interpret the GD542x datasheet correctly they removed generic colorkey transparency on the GD5429 and kept transparency only for mono->color expand? (GR30 register, page 9-55)
Seems like an odd thing to do but maybe it wasn't needed for Windows acceleration except for color expanded text?
And these models where probably from before games where doing transparent hardware blits via DirectDraw.

But it still seems weird to just remove stuff :)
Or have I missed something in the datasheet @PhilC ?

I have verified that colorkeyed blits does work on the GD5426 and could be suitable for blitting game sprites in a speedy fashion.

[PhilC]

@agranlund yes I noticed that in the table and found it and odd thing to have been removed.

Edit: could be that it's still there on the 5429 but doesn't work correctly.

[agranlund]

I chased more red herrings than I care to admit today, but in the end I did find a more or less suitable location to hijack Nova VDI's scroll routine for VT52 console. Cirrus and WDC cards are now scrolling it quite fast with the blitter :)