Re: Cinematronics sound board behavior...

On Wed, 23 Jun 1999 12:56:41 -0700 (PDT), you wrote:

>> >> This is a cool offer! Neil has worked out many of the problems of
>> >> using samples to emulate analog sound boards.
>> >> The source won't be usable on the Scenix, but the logic flow will.
>> >Why not? Is it not C?
>> I believe you can get "C" for the Scenix, but Scenix "C" is going to
>> work a bit differently than anything that runs on a PC.
>
>Oh, I get it. Scenix is a device, not an operating system. ;-) It just
>sounds like another UNIX.
>
>> No Data Stack. (Passing variables to a subroutine is tricky for the
>> compiler and steals some of your RAM variable space.)
>
>Sounds like the 8051 C compilers.
>
>> Very limited RAM memory (don't even think of an array in RAM!,
>> like a pre-buffer for mixing!)
>
>Like the 8051!

The Scenix is a fast running PIC clone. (They even got sued for it.)

It's quite a bit more primitive than the 8051. I believe the 8051 has
a 16 bit pointer (The 'dptr'?) that can be used as a data stack, not
to mention a separate stack pointer, the ability to address external
memory (RAM and ROM), a von neuman architecture that allows for easy
access to data tables in code space. It can easily handle a "C"
compiler (including re-entrant and recursive code -- try that on a
Scenix!)

>> Another IRQ task could supply the data to the DAC as needed, with a
>> foreground task doing the mixing/level shifting, keeping a very small
>> (4 to 8 byte) buffer full for the DAC.
>
>It could do on-the-fly mixing. There's no reason to have a post-mix
>buffer. The only reason that's done now is because that's what all OS's
>want. A simple add+add+add+add+add/clip would work nicely (and does, I
>might add).

That's what I figure and what it sounds like Clay was planning on
doing. If you start with smaller samples you can avoid the 'clip'.

>> the CCPU), doing the waveform playing logic, the mixing, etc. and
>> sending the results back to the scenix which could buffer and play the
>> sounds out the DAC. An 8051, Z-80 clone, etc.
>
>Why not use a Dallas 320? They're 3 clock and go up to 40MHZ! I don't know
>about pricing, though. We'd have to bankswitch the snot out of things, but
>I don't think it's all that evil.

It sounds similar to the Scenix that runs a 50mhz. But I'll bet Clay
wants to play with a Scenix and is looking for an excuse to get a
development system. (Good bet, since he's said as much!)

I'm not sure how Dallas deals with onezy twozy people, but through
Parallax it's pretty easy to onezy twozy Scenix parts.

>> But however it's done, I'm willing to work out all the interface logic
>> for all the sound boards.
>
>And I'm willing to write the code...

Man! Be very careful what you volunteer to do! Somebody want to get
this in writing? WAIT! It IS in writing!! Hee! hee!

-Zonn
Received on Wed Jun 23 15:58:57 1999