exxos's Atari, Amiga & retro forum

Not sure if @thorsten.otto or @BlankVector have any idea whats going on here ?

Note this is when the CPU is running 50MHz, something is tripping up and no idea what Though EMUTOS does seem to behave better with Ultrasatan than TOS206.. no idea why ?


Oddly I can load a PRG a few times just fine, then it gets corrupted... note that the HDD doesn't work at all in TOS206, it mostly attempts to load the drive and crashes.


Mostly just seem to get random errors which doesn't help


EDIT:

So far, EMUTO & 40MHz OSC seems to mostly behave. TOS206 just seems to give garbage at power up and doesn't boot with ultrasatan plugged in .

Humm, hard to say... Indeed, this looks like random crashes. Maybe RAM issues?
On first screenshot, SR=2400 means that the VBL interrupt is being processed, maybe this is a clue... But there is nothing similar on other screenshots.
Definitely, something is unstable. But what?

@BlankVector

It seems more stable now with TOS206, but EMUTOS keeps coming up with this every boot now ?

I think that was a bad connection above

EMUTOS, 104 & 206 All behave the same now, in that when ultrasatan is plugged in, the floppy drive stops working

I've had the floppy issue too. When I use MSA converter to unpack an MSA file to a floppy disk. It displays gibberish unless I reboot and then the disk contents looks normal. I only use the floppy drive to appease notator as it automatically checks for a disk and for converting MSA files. If I try and mix hardisk and floppy ie. backing up notator songs on the floppy I just wind up with corrupted files so I started keeping them separate.

@BlankVector

While doing some tweaks, I ran into this now just after EMUTOS boot screen, any ideas whats tripping up ? oddly it can pass all tests in the diagnostic cart...

Well, I'm not Vincent, but I'm a bit familiar with EmuTOS, too.

It crashes somewhere in the floppy code, presumably somewhere where it's setting the drive and side selection lines of the YM2149 (PSG). (Telltale sign: the contents of A0.) The crash cannot be located more exactly, because we don't know the exact EmuTOS version (+ language) that you're using in your tests.

Now, why does it crash? We can say with certainty that EmuTOS does not contain any "illegal instructions" in that bit of code. Therefore, it must be something related to your hardware setup. Simply a corrupt ROM image? Or maybe accessing the YM2149 somehow disturbs the accelerated CPU's access to code in ROM? (Note that the YM2149 is somewhat special because it's the only(?) peripheral in the ST where an access takes an odd number of 8 MHz cycles: http://atari-forum.com/viewtopic.php?f= ... 1&#p338191.)

Ah yep, I keep blaming the DMA and forgot about the YM chip I mostly get 4 bombs when it tries to access the floppy with TOS206, but sometimes a row of bombs, and yes, this is hardware tripping up ; )

Four bombs is Atari TOS's way to signal an illegal instruction. Maybe your booster is trying to read the next instruction from ROM while the YM2149 access is not yet finished and data bits "mix" on the bus? Like I wrote before, any YM2149 access will have a waitstate inserted into the bus cycle.

czietz wrote: ↑Tue Jan 21, 2020 7:36 pm Four bombs is Atari TOS's way to signal an illegal instruction. Maybe your booster is trying to read the next instruction from ROM while the YM2149 access is not yet finished and data bits "mix" on the bus? Like I wrote before, any YM2149 access will have a waitstate inserted into the bus cycle.

I solved the issue, I wasn't using ST_AS on the SND_CS code