The Sinclair QL Forum

Jbizzel wrote: ↑Sun Mar 10, 2024 1:01 pm Can a bbql make these sounds?

I understand the donkey Kong arcade machine uses the same chip as the QL to drive the sound, so maybe this is possible?

Kef Schecter
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video game history enthusiast and retrogamer3y
Wow, I was practically born to answer this question. A few years ago I reverse-engineered a good chunk of Donkey Kong’s sound program, you see. https://github.com/furrykef/dkdasm/blob ... ng-snd.asm

Donkey Kong’s music and a few sound effects are produced using an MCS-48 chip, specifically a clone of an Intel 8035. This is a CPU much like any other, though it is a very simple one—what we call a microcontroller. The program for this chip takes as input what sounds to play, and it generates the waveform in real time as output.

There’s just one problem with outputting a waveform that way: it hogs the CPU. This meant that the program could only handle two sound channels at a time. Because of this, and possibly other limitations, they added a few TTL circuits to produce additional sound effects, like the sound of DK beating his chest or the sound of Mario jumping. By TTL, I mean these sound effects are produced using pure logic gates, like AND and OR gates. No doubt this required a lot of chips, and indeed, you’ll see a lot of chips on the motherboard. (If you ever looked at the game’s specs in MAME and wondered what “discrete sound” meant, it’s talking about this.)

Donkey Kong Jr.’s sound hardware is the same as Donkey Kong’s, except different TTL circuits are used in order to produce different sound effects. Mario Bros. also uses much the same hardware, except it uses a different, faster MCS-48 chip and its TTL sounds are different yet again.