From:	jerry AT eteklabs DOT nospam DOT com (Scott "Jerry" Lawrence)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro: Adding background music to old DOS game
Date:	Tue, 10 Feb 1998 10:29:58 -0500
Message-ID:	<MPG.f4a3c8070dde98f9896e6@gateway>
References:	<6bphi4$8r6$1 AT fu-berlin DOT de>
Organization:	e-TEK Labs
NNTP-Posting-Host:	dial-q-14.netacc.net
Lines:	32
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In the past, brenner AT biochem DOT mpg DOT de thusly spoke...
> [ ... ]
> 
> Now I'm a beginner in coding DOS system functions (though I did quite some 
> extensive Assembler programming on the Amiga some years ago) and after trying 
> to grasp the basic concepts of the Allegro library I concluded it would be a 
> wise idea to ask the professionals if this is possible using Allegro/djgpp at 
> all :) From what I learned so far it's pretty tricky to do complex tasks like 
> changing the running song in the MIDI routines *from out of an interrupt*, can 
> you give me some suggestions as how to do this? (Can I call the play_midi() 
> function from out of an interrupt handler? I'm pretty sure, I can't ;) Is 
> there an easy way to do this anyway?) How about the 0x21/open interrupt. Do I 
> use Allegro's _install_irq() routine to install my own handler?

Now i'm not positive about any of this, but chances are that Ultima grabs
all the hardware it can - including the timer interrupt (IRQ 0 i believe)
which is also mirrored at int 1ch.  My guess is that Ultima mucks with 
these, disabling any previously installed handlers.  

another thing to look out for is if you're using a soundblaster, there's 
a possibility that allegro will lock the hardware, so ultima will have
no sound whatsoever.

you might want to try making a simple TSR using allegro (which will end 
up taking a large chunk of conventional memory i would think.) that just
plays a note every half second or so... then run ultima.  you'd know
right away if it would work.  THere are docs on the net about making
TSRs in DJGPP.  

or i could be wrong...

	-jerr

- Raw text -