Raven. A homemade Atari-like computer

[atari030]

That is one of the coolest thing's I've ever seen. Nice one.

[agranlund]

Is it a proper Atari now?



It's a work in progress based on my Vampire port of Castaway.
There's no frame-pacing yet so the emulator runs much too fast -- but I thought it was awesome when the first ST game booted and wanted to share anyways

[TheNameOfTheGame]

Looks like a proper Atari! That's exactly what happens when I try to play Arkanoid 2 .

[frank.lukas]

Nice ...

How did you make it possible to make games run on the et4000 graphics card and the 060 CPU? Is it an ST-Low resolution?

[agranlund]

Nice ...

How did you make it possible to make games run on the et4000 graphics card and the 060 CPU? Is it an ST-Low resolution?

It runs under 'partial' software emulation - in that it can route some IO access directly to the host when it has compatible hardware.
On hosts without Atari compatible graphics (such as this) it needs to emulate it. In this particular case it sets the et4000 to 320x200x8bpp and performs planar->chunky conversion to emulate ST-Low.

The target 68000 CPU is software emulated but takes advantage of the host CPU also being of the 68k family so that part is really quite fast.

Code was originally based on the old Castway emulator but with optimisation specifically for emulating Atari on Atari-ish computers. It does trade accuracy for speed and in terms of compatibility it's very far from Hatari levels.
But it does allow some Atari ST games to be played, and at full speed, which is the important bit

Edit: I originally made this emulator for Vampire, but also made sure it could run on 'real' Ataris such as the Falcon CT60.
(And my 520ST+TF536 but there it runs at about half frame-rate )

I made a test build for Firebee sometime last year but it was reported to crash on startup and I can't be bothered trying to debug something without access to hardware. Though I see no reason why it shouldn't be able to run full speed on Firebee/Milan/Hades if someone added support for these hosts.

[mrbombermillzy]

I cant stress enough how phenomenal all this is.

Im aware of your version of CaSTaway (which Im also still awaiting a release of to try on my Vampire v500).

What I want to know is how long you have been working on this new computer system?

[agranlund]

I cant stress enough how phenomenal all this is.

Im aware of your version of CaSTaway (which Im also still awaiting a release of to try on my Vampire v500).

What I want to know is how long you have been working on this new computer system?

Thank you kindly! I'm very proud, and also a bit surprised, that it actually works at all
I was curious too so I had a look through what old files I still had. Thank you for that, it's nice to have and keep around.

I've had a hard time knowing myself when exactly it became what.
It started out supposed to be a 68030 computer, and at some point I thought it would be neat if the CPU was on a separate card, maybe even allowing me to use existing big-box Amiga CPU cards.

November 2023; Raven 68030 with CPU card connector

early_030_small.jpg (45.39 KiB) Viewed 8337 times

That CPU card idea derailed the entire project for a while because that got into my head that I wanted to make a 68060 accelerator for my ST instead. Parts of December was spent on that

At some point I came to my senses and went back to wanting to make a full computer, but I couldn't quite drop the 060 idea.

January 2024; Restarting as Raven060 and it's been a pretty straight road from that point on.
At this stage I was mostly moving the large bits around to make a rough placement plan for the future, to minimise layer-jumping for the important / fast stuff.

early_060_small.jpg (22.87 KiB) Viewed 8337 times

The absolute biggest challenge was routing the board. There was much routing, ripping up, moving/rotating, re-routing over many evenings
Granted, that became faster and faster the better I became with KiCad - I had been an Eagle user up until this project.

[agranlund]

Received an ATI Mach32 today and holy crap...
From these numbers I must assume the Nova driver is able to take advantage of that cards acceleration features.

gb_mach32.jpg (97.97 KiB) Viewed 8188 times

This was the ET4k

gb_et4k.jpeg (74.83 KiB) Viewed 8188 times

It's not a like-for-like comparison since the older ET4k benchmark was using the nvdivga driver and I've since changed to Nova drivers (though the ET4k is actually slightly slower than with the Nova driver)

Ok, so now it's going to be interesting to see how fast I can push the bus. It's still running with waitstates adjusted for the ET4k.

(Gembench seems to crash with copyback cache enabled so those RAM speeds measure a bit lower than normal)

[exxos]

I doubt you would even see the tests running going that fast

[frank.lukas]

Install NVDI5 with the screensys driver in the GEMSYS Folder disable by rename these to *.syz ...

NVDI must run after sta_vdi.prg and you becomes 200% speed from the Nova driver ...