Most versatile 8bit chip synth

Sounds fantastic. The waveform visualization is cool.


Voodoo People! by Kamil Wolnikowski (Jammer)

Slightly surprising to me when I first found out: a SID player needs to include a 6502 emulator, because a chip tune is, or can be, more like a program than a sequence of notes. There’s a thread here all about deconstructing the SID at a transistor level, which includes a link to an interview with Bob Yannes, the inventor of the SID.


First a – maybe somewhat controversial, but this reflects my authentic feelings about this, so bear with me – disclaimer: While the C64 was my first “real” computer (besides a previous pocket computer), and I still have it, I was never that great a fan of the SID. To me, it was in a somewhat uncanny valley, between the usual, clearly artificial and cheesy 8-bit sounds and what can be done on a “real”, full-fledged synth. (Actually, I find some of the game tunes more pleasing on other, competing platforms.)

That said, that tune is fantastic (at least in demonstrating what can be done) – and I may have to revise my opinions.

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As an aside as he’s plugging someone else’s track in that tweet, I used a couple of LukHash tracks for my pre-roll for online lecture last semester, and I have We are Stardust on minidisc sitting right here. He’s definitely a talented composer, in my opinion.

At a slight tangent, …

the chip the BBC Micro used, the SN76489 is a relatively simple sound chip, and at the time it was end-of-lifed and I remember folks saying that SID was far superior - however with just 3 square wave channels and a noise channel it was OK - the clever stuff was all done in software on a 100Hz interrupt to dynamically change frequency and amplitude to great effect…

BBC Micro emulators can emulate the 3 tone channels and noise channel relatively easily as the software does the clever stuff and as long as they have a cycle accurate 6502 emulator it works well.

Some years ago I wrote my own BASIC in C designed to run under a Unix/Linux system. I was asked to provide sound for it… Foolishly I said I’d make it like the Beeb. How hard can it be…

I ended up re-learning, and learning more now that I did back then about the Beeb sound, the 14-parameter ENVELOPE command and so on. It wasn’t trivial as I wasn’t emulating Beeb hardware or software. I ended up “just in time” synthesizing 20 seconds of sound based on the envelope for each channel each time a sound was played, then throwing that at the generic “play a WAV” library I was using (SDL) - as modern PCs just play samples rather than have those old style sound chips now…

It sounded close enough to a real Beeb that I was happy. It wasn’t quite the same though, possibly because I was using a sine wave as my base rather than a square wave, but I never got round to testing different waveforms.



I’m sure to some extent people will always have a favourite, often the machine they first bonded with. I’m in the Beeb camp generally - but the SID really is different, in the sense that the pitch control is musically accurate, whereas the '489 is not accurate for higher notes. Also the SID has different waveforms to choose from: it’s no accident, it was designed by someone with experience in the field (“One of the reasons I was hired was my knowledge of music synthesis was deemed valuable for future MOS/Commodore products”)

All the same, there’s a heroic effort here to play SID tunes on a Beeb:
BBC Micro SID Tunes

For musicality on a Beeb, there’s BeebOPL, and the marvellous Music 5000.

For in-browser demos, as a sample of the present demoscene on the Beeb (using the '489) see


I think the main reason why SID music is so enduring is simply because its sound is very distinctive and immediately recognizable in a visceral way.

I mean, obviously the fact that the C64/C128 sold a ton of units is a big factor. I think NES chiptunes are popular on that alone (the NES sold a ton more units than the C64 ever did).

But the SID sound stands out compared to the competition which had superior sound chips, and the competition with slightly less flexible capabilities all have a relatively similar square wave sound.

This is the interesting point: as a 3 channel Moog-type synth with filters and ADSR envelope (and more filters and effects possibly applied in software) it shouldn’t be that distinctive, but it is. It’s a bit like seeing a calculation and saying, “this is clearly computed on a 286, love that result”. How much of this is owed to a specific subculture? (That tune suggests, quite a bit. But the emulation may help by obfuscating some of the more typical resonances.)

One oddity with the SID is that it came in two (or more?) versions which have - to the connoisseur - distinct sounds. So when emulating or planning a chip replacement, you need to decide which SID to be, or even provide a mechanism to choose between them.


The SID has various limitations which tended to force certain choices, like a lack of true individual voice volume control. The triangle and sawtooth waveforms stick out like a sore thumb next to anything with only square waves, but it lacks any other typical waveforms (such as a sin waveform). There are a couple weird waveforms though, I think.

Quite a bit, but not all. The SID, in all its variants, could never be described as a particularly “clean” synthesizer. It’s at the mercy of the built-down-to-a-price hardware and especially the quality of the power supply. The SID’s distinctive burr (especially when played just slightly too loud out of not-quite-the-best-quality TV or monitor speaker) is as much of a signifier of a time and place as the grotty noises musicians were squeezing out of EDP Wasps around the same time.

Standard demoscene SID tunes get really samey after a while (mostly due the age and tastes of the authors), but a SID or two with the right output hardware sounds sublime. Linus Åkesson’s Reverberations might be the best example I know of.

There are some really nice hardware emulations, such as the ARMSID. But like everything hifi, the subjective dominates the argument, and real MOS SIDs are getting rarer and more valuable.

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Another reason might be that – with all its limitations – the SID is quite complex. I remember that it was a real challenge to fit all the available controls with visual feedback on a C64 screen, which posed some obstacle when it came to exploring the SID interactively. Some combinations became more popular and tended to stick, and there wasn’t that much impetus on the software side, since the built-in capabilities were already considerable. (There are some amazing synth programs for 8-bit computers with much more limited sound chips, E.g., compare the second half of this video demoing “5alad” on a NEC PC-8201: NEC PC 8201 - 8 bit FX laptop by 5alad - YouTube . Edit: As I just found out, somewhat ironically this one is a program that originated on the C64!)

PS, if anyone has this program, “16 5alad - FX laptop for NEC PC8201”, I’d love to have it. It was once a free download, but disappeared together with the hosting site and there is no Wayback-snapshot of this.

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It’s worth noting that Reverberations mostly uses 2 SID chips rather than just one (for 6 voices instead of 3 voices), and he adds a convolution reverb effect to simulate how it would sound within a church. So, it’s not the sound you’d get from a Commodore 64 in vaguely normal circumstances.