Slow DSP investigation with DFB1

[exxos]

@exxos do you have the Falcon diag ROM image that you put on your diag cart? If so then that would be useful, thanks.

I think its this one..

Falcon Test v1.27b.zip

(45.34 KiB) Downloaded 6 times

[stephen_usher]

I think its this one..

Thanks!

[stephen_usher]

Well, I've started the disassembly and even the init code is quite different between the source and the ROM image.

[Badwolf]

Looking at the rest of the code in there, the counters for the timeouts etc. seem to be a bit arbitrary, so possibly determined by trial and error. Also, we have to remember that this is at least four versions before the currently used ROM and it looks like a work in progress, so how much of this reflects the code in the ROM is anyone's guess.

True. I was also wondering later exactly how BW is running this ROM. Is it from a real cartridge with the Atari-assumed ROM timings or from the DFB1 flash? Or flash copied to AltRAM? Running the code from something other than the original slow ROMs could well upset those busyloops....

All tests on the real hardware so far have been with Exxos' cartridge.

I've not got around to trying my 'soft' version yet (basically I was trying to build the ROM with a different origin then having a little bootstrap program that loaded the image to that point in memory and jumped to its entry point. I found the bootstrap program difficult to get working. Showing up my low level 68k programming skillz.

BW

[stephen_usher]

Well, slowly getting through the disassembly and the code is *very* different in places to the 1.21 code. I've not get to the DSP test yet, just got through the initial RAM test and sound test so far.

[Badwolf]

Well, slowly getting through the disassembly and the code is *very* different in places to the 1.21 code. I've not get to the DSP test yet, just got through the initial RAM test and sound test so far.

Thanks, Stephen. I think it has the long blit test, for example, but I don't think I ever got to the point the DSP test.

BW

[Badwolf]

I had a bit of time to test Cubase with the current experimental firmware and fast GAL last night.

Initially I copied the cracked version and test song Exxos supplied onto an IDE drive, forgeting that won't work.

The program ran fine, but yeah, no sound output.

I copied it over to a SCSI partition and tried it from there and immediately saw on-screen artefacting. I still didn't get any sound out so I'm not sure I'm doing it right. When I went to quit I got the umpteen bombs.

So changes are the Cubase incompatibility problems are not wholely related to the DSP timing, but there are a few more combinations to test first.

Would be nice to hear *something*, though!

BW

[exxos]

I normally get loud ticking when it loads. All channels should be silent. But its like they are randomly outputting "noise" for no reason at all.

I get the corruption on load, sometime it will start playing the song.. but its corrupted sound and crashes no long after anyway.

[Badwolf]

I think it's corrupted my drives during testing/crashing which is in keeping with it perhaps supplanting the hard disc driver and not knowing what to do with DMA.

I want to wind it back and test various driver/RAM/CPU configurations but for that I'll need my proper Falcon out. The board under test only has 4MB ST-RAM (so can't load the song without TT-RAM) and no onboard CPU (to verify that works first up).

BW

[whomper]

If it is the song I’ve created than yeah, when I load it in DFB mode it does output crackles during wav load, something it does not do in regular mode. It may pass the wav file through the DSP during load which might create those artifacts.

I do however get the song to play but it is more related to audio sample rate. Perhaps you should open the audio settings window and reaffirm settings. Also, the files are 44.1KHz and Cubase requires a hardware sale rate generator to go up from 33Khz