OCS specific issues?

[earok]

I'm having some issues with OCS specifically (NOT with ECS, only tested under WinUAE). On AGA/ECS when I display images and play sound they work correctly, but with OCS I get a grey screen and crackling noises. I'm using the display library but didn't have much luck with slices either.

Any ideas? I can post my project if need be.

[earok]

Ok, I think I've narrowed it down to a memory usage issue - how do you detect that an OCS chipset is installed?

[Daedalus]

I haven't tried any projects on OCS machines unfortunately, but they should work very similarly to ECS machines. How many bitplanes are you using? Does WinUAE emulate the early OCS chipsets that are missing the EHB mode? Maybe that could be causing you issues. Or are you running out of chip RAM on the OCS setup? Are you accessing any addresses directly? IIRC some addresses change between OCS and ECS, so hardcoded addresses for decoding images to might work under one but not the other.

Edit: Sorry, I didn't see your second post, sounds like you're onto something. There are registers you can use to detect AGA but I don't know how to detect the ECS chipset specifically from OCS. Blitz doesn't have a function for detecting chipset versions, but maybe you can check for the required amount of memory being free?

[earok]

I think it's a chipram thing, I wiki'ed it and of course OCS can only access 512kb-1mb of chipram. Whoops!

I've worked it out how to detect it anyway, this seems to work

VPOSR.w = Peek.w($dff004)
AGA = (VPOSR & (1 LSL 9))>0
Chip = (VPOSR LSR 8) & 63

if Chip = $00 or Chip = $10
;Is only OCS
endif

[Daedalus]

Ah, very good. That's the register I remember using to detect AGA, good to know it can also be used for OCS/ECS chip revisions.

[Cylon]

Why does it matter what chipset you are on when you encounter memory issues?

Checking available memory before use is mandatory if you try to max out boundaries.

[earok]

I don't know the ins and outs of it but there is a difference when different chipsets are used regardless of available ram.

I believe it's something like, sound effects need to be in chipram, and the amount of addressable chipram varies by chipset.

[ReadOnlyCat]

Originally Posted by earok

I don't know the ins and outs of it but there is a difference when different chipsets are used regardless of available ram.

I believe it's something like, sound effects need to be in chipram, and the amount of addressable chipram varies by chipset.

All memory used by the chipset is addressed via Agnus which effectively means that this chip dictates the amount of memory which can be accessed by the whole chipset. You should just use the Agnus version number to determine the maximum chip memory range: http://amigadev.elowar.com/read/ADCD.../node00A2.html

[idrougge]

The Agnus revision is the same whether you have 512k or 1 MB of chip RAM, or whether you have 1 or 2 MB of chip RAM.

[ReadOnlyCat]

Originally Posted by idrougge

The Agnus revision is the same whether you have 512k or 1 MB of chip RAM, or whether you have 1 or 2 MB of chip RAM.

That goes without saying, the revision number only indicates the maximum range, not the current amount of memory.