exxos's Atari, Amiga & retro forum

Badwolf wrote: ↑Wed Aug 03, 2022 12:35 pm

alexh wrote: ↑Wed Aug 03, 2022 12:05 pm Perhaps turn off "turbo"?

Can try that as an experiment, but the cycles are quite quantised, so it would need a big change to make any noticiable difference, I suspect.

So running without 'turbo' mode (governor = powersave; frequency = 600MHz), we see data transfer rates of 1.4MB/s (down from 1.8) and a relative RAM measurement in GB6 of 35% (down from 50%).

The fact it's so measurable shows there is a significant Musashi overhead. We may have to go straight to Emu68.

BW

alexh wrote: ↑Thu Aug 04, 2022 12:03 am

I've never even *seen* a Pi4

I think I'll try to shake out as many issues as I can from this and take a peek at the Emu68 stuff.

Another suggestion has been to not wait for confirmation of writes completing, but that would make a mess of the barely-working bus errors again!

Perhaps shortening the write cycle would help, mind.

BW

By ignoring bus errors on writes (bad thing) and just handing it off to the hardware and continuing to process the emulated CPU, I've been able to get writes up to 100%.

There's a fair way to go on reads, though. Average throughput on gembench is up to 68% and, if cheating by switching to 020 emulation that can be snuck up to 75%, but still not good enough.

Interrupts are likely to still be a problem -- not responding quickly enough, I suspect (Frontier looks like its' running under a strobe as the palette changes at the wrong time), but one that can be put off safely for now.

</update>

BW

Looks like you're making good progress. Thanks for all your time. We the community salute you.

I've pretty much come as far as I can with PiStormST -- the limiting factor at the moment is the speed of the Pi.

The ST doesn't let me get away with the shortcuts that work on the Amiga, so I can't quite hit the turnaround time needed to get full speed ST-RAM reads.

Tried many different tricks. No joy. A Pi 4 may be quick enough to do the job, but I can't get hold of one.

Instead, feeling a bit demob happy, I had a play with a 16-bit VGA-resolution virtual graphics card. Just for fun.

Cheers,

BW

..and the most screwy GB6 results ever award goes to...

Badwolf wrote: ↑Thu Nov 03, 2022 10:35 pm Tried many different tricks. No joy. A Pi 4 may be quick enough to do the job, but I can't get hold of one.

@Badwolf, I have a spare Pi4 I could loan you to continue your journey.

Thanks for all your hard work.

Badwolf wrote: ↑Thu Nov 03, 2022 10:35 pm I've pretty much come as far as I can with PiStormST. A Pi 4 may be quick enough to do the job, but I can't get hold of one.

As discussed previously, send me a PM with your details and we'll get you one now on a like for like exchange basis when they become available again.

As for going forward, is there anything you have developed for PiSTorm ST that you can bring back to PiStorm master? CPU state (FC0, FC1 etc.), bus errors and bus arbitration? There are other platforms that require them (Amiga CDTV, Macintosh)

Icky wrote: ↑Fri Nov 04, 2022 6:00 am @Badwolf, I have a spare Pi4 I could loan you to continue your journey.

alexh wrote: ↑Fri Nov 04, 2022 10:31 am As discussed previously, send me a PM with your details and we'll get you one now on a like for like exchange basis when they become available again.

Thank you both. I think I'm a bit PiStorm'd out at the moment, though. I think this is a good natural break until Pi availability picks up again.

That said, if I get the itch before that happens, I'll give you a shout. Thanks!

alexh wrote: ↑Fri Nov 04, 2022 10:31 am As for going forward, is there anything you have developed for PiSTorm ST that you can bring back to PiStorm master? CPU state (FC0, FC1 etc.), bus errors and bus arbitration? There are other platforms that require them (Amiga CDTV, Macintosh)

Bus error handling (which I'm still not 100% is correct -- I think it's using long stack frames even on an 000 -- not sure why it works) cost the Amiga version speed, so would be folded back disabled anyway. Lot of effort for no obvious gain.

FCx could be done fairly trivially, but would need to go through testing, which I can't* do.

Bus Arb is a (relatively) simple mod to the state machine, but again would need testing, which I can't* do.

Reset problem is still not solved as never got out of development mode (where I just Ctrl-C'd the emulator and ran it again)

What I really need to do is go though diffs of each of the files and #define things in and out. Would probably be a full week's work for no immediate benefit to either side.

A determined user could get a system running at the moment, I think, but it's no where near plug and play, so to push to master would be premature IMO.


Cheers,

BW


* May be physically able soon, but not qualified to know all the Amiga corner cases