[Coco] Re: Sierra games with sound!!

[Boisy Pitre]

> Thank you and I would also like to thanks Ken Carlin that renewed  
> my interest for these games. Ken suggested that maybe with your  
> help we could patch the sound module to drive a Sound/Speech  
> cartridge or an Orchestra 90 cartridge to get 4 voice sound and not  
> stopping the action when played. That would be awesome!

I think I'll post this on the list since it's relevant discussion.

I would like to incorporate Orchestra 90 support at the operating  
system level so that any game could take advantage of this device.   
So instead of patching the Sierra sound module to talk directly to  
the Orchestra 90, the idea would be to write a new SndDrv module,  
which is part of the VTIO subsystem in NitrOS-9, to take advantage of  
the Orchestra 90.  The details on exactly how sound information would  
be transmitted to this module is still sketchy, but the current  
interface to sound under OS-9/NitrOS-9 is through a SetStat call  
(SS.Tone) where X:HI holds the volume (0-63), X:LO holds the cycle  
repeat flag and Y holds the frequency (0-4095).  This is probably too  
primitive for robust 4 voice sound like the Orchestra 90, so an  
additional SetStat would probably need to be designed to pass  
additional information.

That would be my approach to this particular feature.  Build support  
in the OS and then all games can take advantage of it.  Yes, the  
Sierra sound module would still need to be patched, but now it would  
use SetStat calls to communicate sound playing instead.

Guillaume, would you post the details of the Sierra CoCo sound file  
format here?  I and others would be interested in seeing them.

Boisy