[sdiy] Synth Chips (OPL)

[Simon Gatrall]

>Byron wrote:
>  > Yamaha have also made several things like this.  There are the notorious
>  > OPL3 & OPL4 (anyone care to refute those part numbers?) FM chips, which
>were
>  > used on a lot of pre-wavetable PC sound cards.
>
>That's true.. I have a lot of these old OPL-chips on broken pc-soundcards,
>and a couple of years ago I even wrote a little opl-sequencer program on the
>pc. I did a lot of weired sounds with them. The trick was not to use one
>operator-pair per voice but all the 11 voices of the chip for one sound
>(e.g. driving that thing in monophonic mode).
>
>I wonder if anyone knows how to use these chips in selfmade circuits.. I
>don't have found a datasheet on them anywhere. It shouldn't be that
>difficult to build a small midisynth with them. Basically I expect nothing
>more than powersupply, data and address busses and an audio-out.
>
>Nils Pipenbrinck

The OPL 4 is actually a 1MB wavetable synth - it also has an FM synth 
engine in it as well, but you have to have an ISA bus to talk to that 
part of the chip.  The GM wavetable part understands plain serial 
MIDI.  I'm using it in the SG20 General MIDI synth for the Palm. 
Yamaha is no longer making the part.

Dream (part of Atmel) also makes some interesting wavetable chips 
that are used in Karaoke machines and apparently some QuasiMIDI 
products.  (Check out www.dream.fr)

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Simon Gatrall
President
Swivel Systems

mailto:simon at SwivelSystems.com
http://www.SwivelSystems.com
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