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Apple II Computer Info

though in that it could only produce sound using pre-calculated

waveforms (squarewave, sinewave, tringlewave and so on) so it

was rather artifical sounding. It was similar to IBM sound cards

like the AdLib and SoundBlaster, only those were much more

advanced and used FM synthesis.

The Apple IIgs:

The IIgs came standard with a sound coprocessor chip built-in

every machine. That chip was the Ensoniq 5503 Digital Oscillator

Chip (Ensoniq DOC). It had 32 oscillators, which could either be

used independantly or paired with others to create richer sound.

The Apple IIgs paired them (with two reserved, for timing control

I believe) and had 15 voices. Some programs unpaired them to get

near 32 voices (e.g. Diversi-Tune) while others paired them twice

to get better sound (e.g. synthLAB, which has 7 voices). Unlike

the Phasor and other sound chips, the Ensoniq could do wavetable

synthesis. In otherwords, it could use an unlimited spectrum of

waveforms to create all sorts of sound variations and of course,

very realistic ones (you could digitize the sound of a real piano

or real violin as a basis for your waveform. Nothing exciting

today, but back in 1986 this was unheard of in a personal computer).

The Ensoniq 5503 worked in 8-bit sound resolution, and could

play back at sampling rates up to 44.1 kHz and even _much_ higher

[I'll leave out any comments about the low pass filter as I'm a

little confused about it presently, as half the people out there

say it is bad, while the other half say its good. Oh, and no need

to repost those article clippings, Supertimer and Scott G. ;-)]

It had both a DAC and ADC built-in, so you could play back and

record digital sound recordings. It also had 8 independant stereo

channels through which each of the 32 oscillators could play

through, potentially giving the GS the ability to have stereo

sound came out of multiple speakers (sound in front, back, sides,

up and down). Unfortunately Apple wired all 8 channels into one

monorail channel through the 1/8" headphone jack, but they made

the signals available through a molex connector on the mainboard.

All existing third party stereo cards only decoded two channels,

so you only got left/right stereo, like most computers and home

audio equipment today.

In summary, while you could do interesting sound and speech

with the Phasor card, the Ensoniq chip in the IIgs complete blew

it away (as well as all other computers back in the 80's--and

most in the early 90's). The Ensoniq was a professional music

synthesizer chip, the same one used in the Mirage keyboard. It

could do everything the Phasor was capable of, including speech

synthesis, not to mention even emulate the Phasor's AY-3-8913

chips. Today its fairly obsolite compared with modern versions

of the Ensoniq and other wavetable chips and technologies (you

can see that if you try to use it to play MIDI files ;-) though

still quite impressive for a 12 year old machine! For example,

you can play 8 voice MOD files using a stock 2.6 MHz Apple IIgs

as the chip acts as a coprocessor (the Macintosh Plus and SE,

with its more powerful 68000 but lesser 4 channel DAC, cannot

play MODs at all).

Mitchell Spector

[email protected]

Apple II Computer Technical Information : Apple II Family Hardware Info

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