Raven. A homemade Atari-like computer

[agranlund]

Inspired by CT60 and Firebee and so on I tried running the graphics card VGA-Bios in an x86 emulator at boot, before the OS is started.

That worked surprisingly well and faster than I expected!
EmuTOS, built without graphics card init code, runs fine.



The practical use of all this is quite low, or at least unknown.
In practice, you still want to use NOVA to get a VDI capable of working with nice screen modes. Not to mention the hardware acceleration it supports.
And if you do that you already have a card that EmuTOS is able to start up.

At best, perhaps it would allow you to use just about any VGA compatible ISA card in a B&W EmuTOS desktop.
But perhaps the code could be used as a base to develop some kind of works-with-most-cards driver, in combination with NVDI so one didn't have to write a whole VDI too. Card setup and SVGA functionality are otherwise quite custom per card and to get that stuff almost for free like on PC has to be a benefit.

Perhaps it could come in handy if one wanted to make Raven do something completely different than run TOS and you also wanted graphics.

Regardless, it was a very fun experiment even if I'm not sure what to do with the result at the moment

[peters]

That looks like the sort of work that might be needed to get the Radeon to work in the Milan.

[danboid]

Brilliant stuff!

Take another victory lap Mr G!

[Badwolf]

I swear you have 48 hours in your days, Anders!

BW

[agranlund]

I swear you have 48 hours in your days, Anders!

Nah, I'm just good at quickly scrapping together stuff from pieces made by others. Standing on the shoulder of giants and all that.


I tested the different cards I have available and this method got me a desktop on all of them:
Mach32, ET4000/W32i, ET4000AX, Cirrus Logic GD5426

Pretty cool to see that GD5426 spark to life!
And now I couldn't resist so I ebay'ed a few random cards with other chipsets to have a go with too

Of course this is just standard VGA so nothing exciting in terms of fancy desktop resolution.

Making the cards go into SVGA mods would require at least a some different code per chipset, but probably nowhere near as much effort as if you had to do it without help from the cards bios. It's still going to end up being an (x86) SetMode call that performs the bulk of the work even for SVGA.
And then I guess you'd have to tie something like that together in an fVDI or NVDI driver so TOS can draw to the pixelformat too.

Not sure I'm willing to go that far with this experiment but I do think I will move the bringup mechanism into Ravens boot-rom at some point. Since it already supports more cards it makes sense that it does it rather than letting EmuTOS do it.

Any sane person would still launch NOVA-VDI and use one of the cards supported by that though.

[peters]

Where did you get the x86 emu and how did you run it ? Could it be run from Mint or the TOS ?

I might attack the Milan this weekend and fit the Radeon I have.

[frank.lukas]

This is a very nice ISA Card with 2MB of Video Ram ...

V7-Mirage.jpg (515.97 KiB) Viewed 597 times

I think it is a S3 86C801

[Badwolf]

I swear you have 48 hours in your days, Anders!

Nah, I'm just good at quickly scrapping together stuff from pieces made by others. Standing on the shoulder of giants and all that.

Haha, you say that but, for example, I've been off-and-on working on your Hyper68k codebase trying to understand it and port it to the Falcon/DFB1 (nb. works now in Hatari, but not on the real Falcon). This isn't even inventing something, it's modding it. It's taken me months of half-hour here and 15 minutes there.

You've definitely invented new days in the week to turn things around!

Making the cards go into SVGA mods would require at least a some different code per chipset, but probably nowhere near as much effort as if you had to do it without help from the cards bios.

Absolutely. It's the way to go if you were so minded!

BW

[agranlund]

Where did you get the x86 emu and how did you run it ? Could it be run from Mint or the TOS ?
I might attack the Milan this weekend and fit the Radeon I have.

I grabbed the core code from Firebee sources and only had to do extremely few setup and call-out changes to suit my purpose with ISA instead of PCI.
https://github.com/firebee-org/BaS_gcc/ ... ter/x86emu

Firebee team got it from NetBSD, and they in turn got it from SciTech's old MS-DOS sources.
I'm pretty sure the one in XFree86 for Linux is a derivate of SciTech's too.

Pretty much "everyone" calls into vgabios through some kind of bare-bones x86 emulator, even on actual x86's because it's RealMode code.
Today is probably completely different with EFI having replaced the old PC bios stuff.

[peters]

Thanks, I may have to fix my gcc build environment which looks like it's lost a load of libs.