4 ms·

Literally (yes, using the word correctly here) just wondered today(!) how the sounds for Defender were created. I have a sound board from an original Williams

Literally (yes, using the word correctly here) just wondered today(!) how the sounds for Defender were created. 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.

Samsay 2y ago
The first word is used in a wrong context, makes no sense here . It is an extraordinary good example of wrong use of the word. There is no metaphor in that sentence that could be a meaningful reference for that first word.
- JKCalhoun 2y ago
  Yeah, I guess there isn't a metaphor, ha ha.
msarnoff 2y ago
“A friend made a 1-bit synthesizer” Hi John :) https://github.com/74hc595/1-Bit-AVR-Synthesizer 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.
- msarnoff 2y ago
  (Not a typo: 6800 with two zeros, not the 68000 of Mac and Amiga fame. The 8-bit 6800 is mainly famous for getting completely undercut by the 6502 and thus never making it into any home computers.)
- JKCalhoun 2y ago
  Ha ha, hi friend! Yes, it was your awesome synth I am recalling. How are you doing? And thanks for this distillation of how the sound code worked. You're name-checked in the YouTube video linked in this thread. 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."
  - msarnoff 2y ago
    I have 2 kids now (a toddler and a newborn) so I don’t get to hack on stuff anymore like I used to. I’m teaching my oldest about all the classic retro games though… if I ever get my Mac LC back from my parents’ house I’ll introduce him to Glider :)
    - JKCalhoun 2y ago
      Congrats on the kids (and married too I assume). 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.
joezydeco 2y ago
There's an incredible video where this individual breaks down how the sound board works while also resurrecting the source code from the leak that came out a while back. https://youtu.be/ZRDdKZ7V54I https://youtu.be/ZRDdKZ7V54I
- JKCalhoun 2y ago
  Deep dive. Thanks.

Samsay 2y ago

The first word is used in a wrong context, makes no sense here . It is an extraordinary good example of wrong use of the word. There is no metaphor in that sentence that could be a meaningful reference for that first word.

JKCalhoun 2y ago
Yeah, I guess there isn't a metaphor, ha ha.

msarnoff 2y ago

“A friend made a 1-bit synthesizer” Hi John :) https://github.com/74hc595/1-Bit-AVR-Synthesizer 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.

msarnoff 2y ago
(Not a typo: 6800 with two zeros, not the 68000 of Mac and Amiga fame. The 8-bit 6800 is mainly famous for getting completely undercut by the 6502 and thus never making it into any home computers.)
JKCalhoun 2y ago
Ha ha, hi friend! Yes, it was your awesome synth I am recalling. How are you doing? And thanks for this distillation of how the sound code worked. You're name-checked in the YouTube video linked in this thread. 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."
- msarnoff 2y ago
  I have 2 kids now (a toddler and a newborn) so I don’t get to hack on stuff anymore like I used to. I’m teaching my oldest about all the classic retro games though… if I ever get my Mac LC back from my parents’ house I’ll introduce him to Glider :)
  - JKCalhoun 2y ago
    Congrats on the kids (and married too I assume). 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.

joezydeco 2y ago

There's an incredible video where this individual breaks down how the sound board works while also resurrecting the source code from the leak that came out a while back. https://youtu.be/ZRDdKZ7V54I https://youtu.be/ZRDdKZ7V54I

JKCalhoun 2y ago
Deep dive. Thanks.