[Coco] Orchestra 90cc High Speed Mode

[Bill Pierce]

High Speed Orch90?
Wow, didn' know about that one. I'll remember that when I get back to writing the Orch90 player for Sound Chaser. I had to take a break from working on it so I could get some other projects done but will continue after the first of the year.
I was trying to disassemble the Orch90 rom but according to Jon Bokleman's email I recieved a while back, the code was writen on a Model I and cross assembled so it's all over the place. Instead, I've opted to write my own code based on the knowledge of how the original works. Which is basically like Musica but more in line with the way Lyra does TV play in the last incarnations of the program. The major difference is that both Lyra and Musica decode the music as they play, giving them a grainier sound. Orch90 decodes (scores) the music first into playable code then plays. The other major difference being 2 8-bit dacs as opposed to 1 6-bit dac. Sweeeet.
My "playmus2" player for Sound Chaser will play Musica files in full stereo through the Orch90 (real or VCC emulated). I think since it runs in Level 2 OS9, the high speed is already in effect. I know it sounds awsome.

Bill

Music from the Tandy/Radio Shack Color Computer 2 & 3
https://sites.google.com/site/dabarnstudio/
Bill Pierce
ooogalapasooo at aol.com




-----Original Message-----
From: Rogelio Perea <os9dude at gmail.com>
To: coco <coco at maltedmedia.com>
Sent: Mon, Dec 10, 2012 6:41 pm
Subject: [Coco] Orchestra 90cc High Speed Mode


>From an old Delphi conversation:

- - - - - - - -

10024 1JUL86-1959 Hardware Hacking
RE: POKE65497,0 (Re: Msg 10012)
From: ARTFLEXSER To: MARTYGOODMAN

Actually, that double-speed mode does work pretty nicely with the
Orchestra-90 rompack, which has an undocumented command (shift-enter) for
throwing it into that mode. So long as the code being executed is not in a
tight loop (which can be planned for by the designer), the all-ram
double-speed mode does a nice job in enhancing the music quality. Though,
of course, not every CoCo will run properly with it. (Memory will get
refreshed okay in the course of executing instructions
- - - - - - - -

Always been intrigued about the details on this high speed mode, now that I
have been playing with the O90cc pak for the Holidays music the thought
came up again: what exactly does that SHIFT-ENTER sequence engage when done
at the pak's boot screen? is it supposed to throw a CoCo 1/2 into the all
ram double speed?

It apparently does nothing in my F board setup... need to record and play
back head to head two music renditions to see if any HF aliasing smooths
out or not when in that mode.

>From Basic the F board's video goes bonkers as expected on the POKE&HFFD9,0


-- RP

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