The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
the Ground Apple II archive, 1997-2003. Administrator: Steve Nelson
Csa2 FAQs-on-Ground ref: Csa2SOUND.txt rev069 December 2003
Sound & Music
001- How does the GS produce so many simultaneous sounds?
002- Is there a way to output quadraphonic sound on a IIgs?
003- Do I get Stereo from my IIgs Sound Output jack?
004- Why should I add a stereo board to my GS?
005- How can I build my own GS stereo board?
006- How can I transfer sound files created on a Mac to my GS?
007- How do I program a Phasor Sound Card?
008- What is required to build a Sound Input board for my IIgs?
009- What's what re. MockingBoard hardware and programming?
010- How do I get my MockingBoard to work on my GS?
011- How do I play Ultima IV/V with MockingBoard sound on my GS?
012- How can I get 'regular Apple sound' to play through MB outputs?
013- What GS programs will let me play MIDI files?
014- Would FExt.NDA let you play thru Synthinit?
015- Can I play .WAV files on my GS?
016- What formats are used for audio files?
017- How do I use my Echo speech synthesizer to produce speech?
018- What types of sound files are used on the GS?
019- Where can I find more info on cards, editing, digitizing, ...?
020- What is "old Apple" sound and how is it produced?
021- What is a good source for .WAV and .BNK files?
022- How can I get more System Sounds for my GS?
023- How can I run Music Studio 2.0 from hard disk?
024- How can I record better sound samples on my IIgs?
025- Squeals and other noises spoil my GS stereo board sound? A fix?
026- My IIgs has no sound from the internal speaker. What's the fix?
027- Where can I find GS music and music creation programs?
028- Does any Apple II emulator include Mockingboard support?
029- Does anyone know what a "Supertalker" card is used for?
030- My GS stereo board's sound output is very low and noisy. A fix?
From: Todd Whitesel
001- If the GS only has eight output chanels, then it would
seen to me that it could only play eight different sounds
at a time. So how can I digitize fifteen different sounds
and play them all back simultaneously?
To summarize the following lecture:
There are 32 oscillators (16 generators) and 16 channels. Not all are used for actual sound output.
Oscillators are "smart voices" Generators are oscillator pairs that can generate extra effects with each other Channels are actual independent output lines like left and right speaker
That said, let's start at the top.
The DOC is a coprocessor with its own dedicated 64K of RAM. All the sound samples have to be put in this RAM before they can be played.
The DOC has 32 'oscillators' which are essentially smart DMA channels. Their basic function is to sweep through areas of the DOC memory reading samples and playing them. They can do so at variable speeds (automatically repeating or skipping sample values as necessary), they can loop on a power of two boundary, they can stop when they read a zero, they have independent volume settings, and various other things that aid in reproducing complex instruments without loading down the main CPU.
But when you come down to it, the DOC is capable of playing 32 sounds simultaneously and indepen