VOGONS

Search

Common searches

GUS mixControl default

Topic actions

First post, by peterferrie

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie

I noticed that the Fallen Angel demo from A-Men won't run in DOSBox unless either the real Ultrainit.exe exists, or any DemoVT-based demo was run first. After much tracing, I see that if I write a 0x0c to the GUS base port, then Angel runs without any depenencies. That suggests something IRQ related. At a guess, I suppose that Angel is assuming that IRQs are always enabled. Would the world break if that was the default mixControl value?

Reply 1 of 9, by wd

Posted on 
User metadata
Rank DOSBox Author
Rank
DOSBox Author

Could you please check if ultrainit.exe does such a write as well (not followed
by a write to gusport+0x0b)?
It might even be enough to use myGUS.ChangeIRQDMA = true; for the gus
initialization code.

Reply 5 of 9, by peterferrie

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie

>Could you please check if ultrainit.exe does such a write as well (not followed by a write to gusport+0x0b)?

Ultrinit.exe (I got the name wrong before) writes 0x0b to gusport, then writes 0 to gusport+0x0b, plus lots of other combinations, too.

>It might even be enough to use myGUS.ChangeIRQDMA = true; for the gus initialization code

I think that it's not a DMA problem, but that the IRQ never fires.
Changing the mixControl value alone (not touching ChangeIRQDMA at all) makes the demo work. Changing ChangeIRQDMA without touching mixControl still hangs.

Go to top of page Go to top of page
Back to DOSBox Development
Close window
Close window