Raven. A homemade Atari-like computer

[agranlund]

@agranlund that's good news. I was going to try and disassemble the vdi drivers at some point and have a go at doing drivers.

I recon I'll put the existing stuff on github during next week or so. I think it should make it trivial to add support for more cards (as trivial as graphics card drivers can be that is )

The middle-layer framework, which sits between STA_VDI and card specific drivers, deals with all the common boilerplate stuff so each individual driver ends up quite small. The WDC and Cirrus ones are both ~300 lines of C code and will be submitted as work-in-progress examples one can base new drivers off.
These are both leveraging the fact that we have vgabios, making the situation quite similar to SVGA in MS-DOS.

When acceleration becomes a thing the idea is that individual driver can supply an optional blit() callback of sort that does only the hardware specific stuff. To be called by that middle layer as appropriate.


The thing can be compiled to include only one specific card driver (+generic vga fallback, this is always there) or to include and probe for all of them. I haven't really decided how I want to package this up for raven yet.
Right now I'm building a monolithic one that auto detects WDC and Cirrus for SVGA support, or falls back to the failsafe VGA-only core.

[agranlund]

I've got a cl-gd5429 and an S3 board to play with at some point.

If you want to give that CL-GD5429 a go then here's the required files attached.
(Anyone else is welcome to test it too of course)

I found two Cirrus cards but they were both GD5426 variants. They had bios from different vendors so it was still quite good for testing but I would have preferred if it was two different models
My cards were both 1MB and goes up to 1024x768x8bpp just fine, as well as up to 800x600 in 16bpp.
Old crappy banked mode is not yet implemented so it requires GD5422 or better for big resolutions.


** The "nova/default" folder goes on the hard drive. It supports "all" cards for standard VGA modes and SVGA when autodetecting a Cirrus Logic. It's a debug build so it should spit out stuff on the serial port.
rvbios will list you a bunch of resolutions but that doesn't necessarily mean they will all work -- i just populated the definitions file with common VGA+SVGA resolutions and in the end it's up to the driver when it gets activated to decide if the mode can be set or not.

** It requires the latest rom which is included.
Apart from the new and required function exports, it also contains general fixes to the x86 emulation;
Gfxcard vgabios's should now be able to detect the correct amount of vram installed on the card.

** There's also the latest Nessi firmware attached but is probably not strictly needed.
Changes:
- ever so slightly less aggressive default isa timing; my Mach32 now passes vgabios initialization without crashing when I use 48mhz oscillator
- jumper J105 is now used to select between normal or aggressive ISA-RAM timing - do not leave J105 without jumper.
jumper topmost two pins for normal mode, which is the same behaviour as before.
jumper the lower two for slow mode, for very old gfxcards which cannot handle our normal (faster than spec) isa-ram timing
(this was added because an old OAK card I was playing with was incredibly unhappy with the fast VRAM access)

The jumper may or may not stay in the end. This is how it is for now because it provided a fast way for me to test but I'm thinking I should just add a register for this which could be set from code.

raven_vga_test.zip

(376.75 KiB) Downloaded 16 times

!Message from: Moderator

@agranlund, we have placed your attachments in-line so they display correctly in your post. Here's the how-to guide.

[PhilC]

@agranlund thanks, will give it a go as soon as I can. I have a couple more CL cards somewhere to try too.

[agranlund]

And an updated emulator.prg

raven_vga_test_2.zip

(7.19 KiB) Downloaded 11 times

Fixes some nasty memory overwrite bugs I hadn't noticed until now.

It also adds an automatic bankswitch system for drivers/cards which cannot natively present a linear framebuffer.
For Cirrus, that means GD5420 and older are now also capable of SVGA resolutions.

That system is unoptimised and could be made faster but it's never going to be blazingly fast. Some access patterns are worse than others.
It also wont work for 16-color planar modes so if the driver cannot do linear then 16-color modes will be capped at 800x600 which fits in a single bank.
Other bitdepths have no such restriction but realistically you probably don't want to run very high resolutions without linear support anyway. Cards without it are usually really old and slow in themselves too so it might be completely pointless

[PhilC]

Just tried the update today, with mixed reviews to be honest.

Just checking I did things right, I updated Nessi, then reflashed the new rom, then copied default over to the nova directory and then replaced the emulator.prg in just the default/auto directory. I was unsure if it should replace all copies of the emulator programs.

Booting with a 1mb S3 and I just get a blank screen. The GD5429 and 5422 I get mono mode just fine and sometimes 800x600x4 but it can occasionally crash.

With my W32 I now can't run doom and get random crashes every so often.

[agranlund]

Thanks @PhilC

With my W32 I now can't run doom and get random crashes every so often.

This is most concerning. I'm assuming you used the W32i driver there so any changes to the nova/default folder would be irrelevant.
Would you mind testing if it was the FW or ROM change that broke this for you?
Perhaps flash the previous FW first and check that since it feels the most likely?

Just checking I did things right, I updated Nessi, then reflashed the new rom, then copied default over to the nova directory and then replaced the emulator.prg in just the default/auto directory. I was unsure if it should replace all copies of the emulator programs.

Yep that's the correct procedure.
When you got a blank screen on the S3, what was the last bits of things the log in the serial terminal said?
(I'm wondering if it died on bios init, or somewhere later on when the driver initialised)
It would be interesting to know what the log said when those Cirrus cards didn't set your modes also and went mono.


Oh, and code is also now on github under the sw/rvnova folder.

[PhilC]

@agranlund I'll give that a go and let you know tomorrow.

I've got a feeling it's Nessi firmware as the system was really stable before I'd updated it.

[PhilC]

Just reprogrammed Nessi with the 240901 Jed and I'm back to normal once again. So looks like my setup doesn't like the new Nessi Jed.

I'm going to try the other graphics cards shortly and will post the results.

[agranlund]

And Cirrus Logic said, "Let there be blits", and there were blits

IMG_5129.jpg (54.3 KiB) Viewed 1192 times

[PhilC]

And Cirrus Logic said, "Let there be blits", and there were blits

IMG_5129.jpg

Wow, nice update. I've managed to get the CL-GD5429 to boot to desktop but only in mono mode. It doesn't like 4 colour 640x480. I get drive icons but then it crashes and I have to press the reset.

The S3 via serial says starting Tos but the monitor never comes out of sleep mode.