[Michael] has a thing for playing audio over beepers using a single bit. He’s done it with the Apple ][ and the IBM PC. This time he turns to the ZX Spectrum. He didn’t get quite as good a result — at least not yet — but he did manage to get some things working. He documents everything, so even though this wasn’t a successful week, there’s sometimes more to learn from reasonable failures than from unreasonable successes.
Of course, the whole thing relies on pulse code or pulse width modulation. Of the two techniques, PWM should produce better results. However, he wasn’t able to get PWM working yet. Some other target computers drive the buzzer through a dedicated hardware timer. However, with the Spectrum, it is all software.
Getting multichannel music was another algorithm, and that makes for an interesting read, too. We are sure next week there will be more, and if you are interested in this sort of thing, going back to some previous weeks will show you a lot more, too.
PCM is, of course, nothing new. Sound output has come a long, long way.