[Coco] OS-9 Level1 Version 02.00.00 FYI

[Allen Huffman]

> On Apr 21, 2020, at 10:08 PM, Walter Zambotti <zambotti at iinet.net.au> wrote:
> 
> Nice.
> 
> I was wondering how the (Nitr)OS-9 sound driver could or does work.  Certainly creating ticks at the required audio frequency is novel.

My sound “driver” for OS-9/6809 was far less impressive. It was just an interface to push data out to the 6-bit DAC. All the driver really did was set up and restore that hardware. It would likely have conflicts if being used by something else that wanted those bits at the same time (joystick/mouse).

But, you could do something like:

merge file.raw >/snd

…and it would play it ;-)  There may have even been a SETSTAT that would let it take a buffer pointer and do it without having to chop it up one byte at a time like SCF did (it was an SCF serial driver).

*** UPDATE *** I found it, and an archive of other OS-9/6809 things I had posted around back then. I just uploaded it all to the CoCo Archive site.

> I was looking at using the Gime timer to create 1/5000 sec interrupts for some low quality audio generation, but I'm not sure the CoCo is even capable of that!

The CoCo 3 has some source to do it, and there are OS-9 programs that mask interrupts and do good sound.

		— Allen