Re: SFX Expander programming and VICE

From: Richard Atkinson <>
Date: 27 Nov 2011 06:12:51 +0000
Message-ID: <>
On Nov 26 2011, Gábor Lénárt wrote:

> Does anybody want to donate a 3812 equipped sound expander cartridge for 
> me?
>:) :) :)

I'm not aware of any YM3812 equipped Sound Expanders other than my own. The 
device comes with a YM3526 OPL. I've met the designer of this cartridge; 
she lives not far from me in Cambridge, UK. Back in 1999 I desoldered the 
YM3526 from my Sound Expander and the YM3812 OPL2 from an Adlib clone, and 
installed the YM3812 in a 24 pin IC socket in my Sound Expander. It ran all 
the standard software just the same as before and since then I've 
experimented with the extra waveforms the OPL2 adds.

An original YM3526 equipped Sound Expander will ignore the accesses to the 
waveform registers and play everything using sine waves. It won't sound 
exactly like the intended wave but you'll still get a sound and it will be 

The first two waveforms (sine and half wave rectified sine) play in the 
same octave, whereas the third and fourth sound an octave above, being full 
wave rectified sine and a rather odd waveform consisting of the same full 
wave rectified sine from 0 to pi/2 and pi to 3pi/2, and 0 at other times, 
i.e. pi/2 to pi and 3pi/2 to 2pi.

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Received on 2011-11-27 07:00:08

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