Defender Sound Studio
zapspace.net
zapspace.net
I have a sound board from an original Williams Defender (maybe the same used in Stargate, Joust?). I have a power supply to run it, a mechanical rotary switch to select the sound you want and a mechanical button to trigger it. I have been meaning to make a nice enclosure for it ... make a cool coffee table ornament.
Always loved those sounds. A friend made a 1-bit synthesizer and you could dial in sounds that occasionally suggested Defender. I assumed therefore the sounds were mathematically generated somehow.
I had tracked down the assembly for the board (probably used by MAME) but had not spent the time to reverse engineer the audio magic. Apparently someone has however.
Very cool. Mind blowing sounds when this game showed up at a nearby arcade — and its sill got it.
That "Game Start" sound is still so stunning. Just playing a bit with it, it looks like "echo" was the killer ingredient.
Hi John :) https://github.com/74hc595/1-Bit-AVR-Synthesizer
I also spent a good chunk of time reverse engineering and reimplementing the 6800 machine code* a while back. It’s pretty brilliant. No hardware timers, everything is software delay loops with controllable cycle counts. (Which is why it’s a bit of a challenge to emulate these sounds; there’s no fixed sample rate other than the CPU clock frequency!)
There are several algorithms. One uses a wavetable approach and then evolves the timbre of the sound by subtracting part of it gradually, until things wrap around and start going crazy. And then there’s one algorithm (which makes the coolest sounds) that is basically two pulse width modulators that interact in some very weird way that I could never figure out.
I got to talk to Sam Dicker and Eugene Jarvis about the sound code when they were at California Extreme many years ago. They brought a printout of the original source code on tractor feed paper.
*The games ran on 6809 processors but the sound boards used a 6800.
Yeah, and to your point, I liked the comment on the linked site:
"The crudeness and lack of bounds checking of the program allowed for mathematical wraparound and error accumulation that sounded ethereal."
Why wait for your LC? Run an emulator. I put a bunch of disk images with the sources and compilers on GitHub that work nicely with 68K Mac emulators.
https://theretrohour.com/williams-electronics-and-designing-...
(It right-shifts by 4 instead of 2.)