Raven. A homemade Atari-like computer

[PhilC]

@agranlund just a thought and I know you hate routing stuff.

How about two IDE headers? 1 for Rach byte swap scenario? They could be right next to each other and won't take up much real estate.

[agranlund]

@agranlund just a thought and I know you hate routing stuff.

How about two IDE headers? 1 for Rach byte swap scenario? They could be right next to each other and won't take up much real estate.

I think I'll keep it as it is now. The normal case is to take advantage of EmuTOS's built in driver, and have the disk readable on both Raven and PC, so it makes sense to be optimised for that scenario in terms of speed.

I'll be able to experiment with non-emutos using the adapter. It could also be possible make a standalone driver out of EmuTOS's internal disk driver, that would solve the same thing.

[dml]

Quick question - what is the frequency of CLK2 to the 2nd MFP? Is it 2MHz divided from the 8MHz clock, or some other value?

And for CLK4?

[agranlund]

Quick question - what is the frequency of CLK2 to the 2nd MFP? Is it 2MHz divided from the 8MHz clock, or some other value?

And for CLK4?

yep, 2 and 4 mhz divided from the 8mhz can.

[agranlund]

@PhilC ,

Firmware binary and some instructions for the USB Eiffel replacement can be found here:
https://github.com/agranlund/raven/tree/main/fw/ckbd

(for this hardware addon)
https://github.com/agranlund/raven/tree ... rades/ckbd

Not everything has been tested, or implemented, in terms of IKBD compatibility but desktop use is working here. I'm sure we'll find and fix incompatibilities as more unusual ikbd modes are tested.

The EiffelCF program can be used for the normal settings but extended stuff (*) will need some new program to be written or perhaps extending EiffelCF.
For now, the Raven monitor can be used to update firmware or change any setting but in a non user-friendly way.
(*) individual scaling for USB, PS2 and Legacy mice. To select Amiga instead of Atari legacy mouse etc.


The ckbd firmware binary is supposed to be in the release package but I haven't gotten around to rebuilding one -- for now it can be grabbed directly from the ckbd folder on github.
Later versions of the raven rom auto-negotiates a higher baud rate when detecting ckbd instead of eiffel so that too goes "live" when I rebuild the release package.

[PhilC]

Cool, thanks @agranlund. Typical you send it after I reassembled my Raven again :p

I'll get some boards ordered and built but will leave the soldering mods for the next time I take it out it's case again.

[peters]

I know pci was left out for good reason but would a CTpci solution work ?

[agranlund]

will leave the soldering mods for the next time I take it out it's case again.

Haha, same here! I still haven't done those to mine - it's a bit of a project removing the board from the case :)

[agranlund]

I know pci was left out for good reason but would a CTpci solution work ?

Anything could work as long as someone is interested in it enough to put the work in I suppose :)
A CT60 compatible expansion port is not a bad idea in itself and you could maybe get a ctpci working that way.

It would certainly be fun to do something more elaborate on a Revision B model but to be honest this one does exactly what it set out to do and provides more than enough fun for me. I recon it will be a long while until I feel the urge to do a larger kind of redesign. In that case I'm leaning more towards a VLB slot but who knows.

[agranlund]

I got a W32i with working interleaved mode and that certainly boosts the internal vram bandwidth.
How much practical difference this makes on an Atari is questionable but I can see this being a big deal on PC back in the day, where pretty much everything automatically took advantage of 2D hardware acceleration and on-card caching of sprites thanks to Windows and DirectDraw.


Bandwidth:
Mach32 vs W32i (interleaved) vs W32i (non-interleaved)
Video move shows a significant difference in vram-to-vram copy speed over the W32i with interleaving disabled.

Kronos_RAM_Mach32.jpg

VDI operations:
Mach32 vs W32i (interleaved) vs W32i (non-interleaved)
We can see that the Mach32 is accelerating more operations compared to w32i.

Kronos_VDI_Mach32.jpg

Gembench W32i (interleaved) vs W32i (non-interleaved)

W32i-interleaved__W32i-standard_hires.jpg

Gembench Mach32 vs W32i (non-interleaved)
We see the Mach32 driver taking advantage of more accelerants here.

Mach32__W32i-standard_hires.jpg

And as an interesting experiment, if we run the test on a lower resolution then the difference becomes minimal and the non-interleaved W32i test is almost the same speed as the interleaved one.
My best guess is that the card is nowhere near starved for vram bandwidth at the slow pixel clock needed for this resolution, together with the tiny area of graphics that Gembench is using for blit related tests.

W32i-interleaved__W32i-standard_lores.jpg