[Coco] SS/C drivers for NitrOS9

[Allen Huffman]

> On Feb 5, 2015, at 3:17 AM, Nick Marentes <nickma2 at optusnet.com.au> wrote:
> 
> I was just wondering if there are Sound & Speech Cartridge drivers for OS-9 and if so, can the Sierra Adventure games be modified to play the music via the SS/C so it sounds more like the other versions on other computers?

That's a really good idea.

There is definitely a driver, and it definitely works with speech. Since it's just streaming ASCII similar to how the RS232 pak or MIDI paks work, I bet it would do the music too since that's how you program the music buffers under RS-DOS.

I expect It would be a minor thing to intercept OS-9's SS.Tone setstat call to use the pak instead of letting the internal DAC be used. Normally, OS-9's tone works like this:

 lda #1		(path 1=stdout)
 ldb $98		(SS.Tone system call)
 ldx #aadd	(aa=volume, 0-63; dd=duration in 1/60ths of seconds)
 ldy #freq		(frequency, 0-4095)
 os9 I$SetStt	(do OS-9 system call)

By replacing this set stat with one that takes the same parameters, but then issues bytes to the Speech/Sound Pak, anything that used it would now go to the pak. Surely someone has done this?

BUT ... software would have to take advantage of it. Assuming Sierra is using this system call (it sounds like they may mask interrupts during the music but I never checked), they sit in a loop sending note after note (it is a blocking call). With an updated driver, it would send all the data that would be built up and played in the background allowing the title screen to continue with music playing. 

Since they all play the same game files (we have several others that were never released for the CC3 after someone - Boisy? - just brought over the game files and used the KQ3 or LSL engine with the data files)... perhaps the code is in there for the background music and it could be made to work.

Interesting. Sadly, the Speech Pak doesn't work at double speed. It requires a mod for that, and mine is not modified. But, if I could get that done, I'd like to play with this.

> Also, does anyone have schematic on a hardware based MIDI interface for the CoCo?

It's an RS232 pak that supports a different baud rate. Take a look a this:

http://www.colorcomputerarchive.com/coco/Documents/Manuals/Hardware/Rulaford_Research_-_CoCo_MIDI%20Pak.pdf

The RS232 pak's baud is controlled by hardware so it does not do the 31500 baud rate that MIDI uses, but there were hardware hacks to change a crystal or something to get that, letting the RS232 pak work as MIDI. It was also possible to send (play only) via bitbanger since the baud was controlled through timing loops.

Glenside did a run of MIDI packs years ago, so I know the plans must be around.

		-- A