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Re: Raven. A homemade Atari-like computer
Posted: 07 Jun 2026 21:17
by redpixel
agranlund wrote: 07 Jun 2026 12:29
I don't have anything particularly clever to add other than I have the same card showing up in ISA_BIOS and working.
That's not saying there couldn't be some kind of incompatibility from Raven or ISA_BIOS but at least a data point showing it working in one machine.
We could probably make an ISA_BIOS with extra debug logging, and maybe a new Nessi firmware with a few more ISA waitstates if that's the issue.
Thanks for the good suggestions! I bought the card just because I saw that you also had it so I was sure that you would do magical things with it :D
I tried to add 2 extra wait states in Nessi, just slapping them onto the "end", i.e. counting up to ISADTACK22 instead of ISADTACK20. That did not make any difference. I also tried to replace the 68150 with another one (the one I normally use is FN40 and I tried to replace it with another FN33 that I have). Also no difference.
Then I tried to use different bus/CPU oscillators, and boom, it showed up! So I guess it is somehow timing related, but it doesn't seem to help adding wait states at the end. My testing looked like this:
| Osc | Nessi 251029 | Nessi +2 waitstates |
| 25 MHz | Detected | Detected |
| 32 MHz | No boot | No boot |
| 40 MHz | Detected | Detected |
| 48 MHz | Not detected | Not detected |
CPU was at X2 in all cases. I have normally used the 48 MHz oscillator. In the No boot case it hangs on InitVga (I'm using an ATI Mach32 2 MB, I believe exact same model as you have also... :P That was by chance though!)
Not sure if you have any ideas what could be wrong, otherwise I can see if I can hook up my logic analyzer and try to measure a bit and see if I can make any sense of it. I think I might have to order one of those ISA extender PCB's for that though, to be able to have some accessible probe points.
Re: Raven. A homemade Atari-like computer
Posted: 08 Jun 2026 00:34
by mikro
agranlund wrote: 07 Jun 2026 12:47
Probably what needs to happen now for a more polished experience is:
- detach mouse cursor redraw from main loop.
some gfxcards has support hardware cursor but for best compatibility I think a software solution like in ScummST would be first priority.
(just redraw the cursor at every VBL if changed, essentially)
- detach music from main loop.
avoid midi/adlib timing jitter as well as stalls if mainloop is busy for a length of time (loading etc)
Perhaps not accidentally, I have looked into same things lately (although only on a theoretical level). VBL based cursors gets *very* tricky once you want to keep triple-buffering in place. Of course, not impossible to overcome and especially if you have true hardware cursors available, that way you don't have to solve dirty rects.
MIDI timing is a bit easier because audio code is assumed to work in a separate thread but then there's the issue I had been fighting for a while (and put it on hold to look into less frustrating things) -- how to actually keep the multithreading part while not stepping into the complex locking/unlocking territory.
But maybe both issues need just a fresh pair of eyes and you are definitely the best candidate for that. ;)
Btw, while waiting for my family at Brisbane airport:

- PXL_20260604_210635204.jpg (173.83 KiB) Viewed 1217 times
;)
Re: Raven. A homemade Atari-like computer
Posted: 08 Jun 2026 07:48
by kodak80
mikro wrote: 08 Jun 2026 00:34
Btw, while waiting for my family at Brisbane airport:
PXL_20260604_210635204.jpg
;)
Wow, that is a big coincidence. :) It's a sign...of good things to come.
Also, guess I won't be getting that rego.
Re: Raven. A homemade Atari-like computer
Posted: 11 Jun 2026 23:47
by agranlund
mikro wrote: 08 Jun 2026 00:34
Btw, while waiting for my family at Brisbane airport:
PXL_20260604_210635204.jpg
Haha, that is amazing!
Re: Raven. A homemade Atari-like computer
Posted: 11 Jun 2026 23:56
by agranlund
Yay! Raven rev.A2 arrives :)
Probably wont have time to solder one up until next weekend or so but was still always exciting to open the package and seeing the pcb as a physical thing rather than a project inside Kicad.

- raven_a2_pcb.jpg (268.16 KiB) Viewed 1051 times
Fingers crossed everything then actually works as intended too :)
Re: Raven. A homemade Atari-like computer
Posted: 12 Jun 2026 00:02
by dml
Nice!!!
Re: Raven. A homemade Atari-like computer
Posted: 12 Jun 2026 09:51
by Cyprian
looks great,
I'm very curious about the DSP itself
Re: Raven. A homemade Atari-like computer
Posted: 12 Jun 2026 09:56
by PhilC
Look at all that black and gold :cheer: :cheer:
Re: Raven. A homemade Atari-like computer
Posted: 12 Jun 2026 11:58
by LarryL
wow - looks extremely beautiful!
Oh my God — how can I stop myself from giving in? :o :roll:
Re: Raven. A homemade Atari-like computer
Posted: 20 Jun 2026 14:53
by agranlund
Slowly, most of the top-layer SMD components are in place.
I had forgotten how much work it was to assemble it... :)

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