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Commodore 64 web synth
February 21, 2014 7:21 AM   Subscribe

WebSID lets you play a Commodore 64 synth in your browser (mobile included). (found via)
posted by curious nu (25 comments total) 21 users marked this as a favorite

 
Waveform? Ring mod?
posted by Wolfdog at 7:39 AM on February 21


I have no idea how accurate this software emulation of the SID chip is, but it does sound pretty cool.
posted by He Is Only The Imposter at 7:44 AM on February 21


I have no idea how accurate this software emulation of the SID chip is
Not very.
posted by Wolfdog at 7:47 AM on February 21 [3 favorites]


I obviously need more sleep as I read the title as Commodore 64 was a myth.

Doesn't sound like anything I remember, though. :| Maybe I suk at playing music.
posted by tilde at 7:50 AM on February 21


I have no idea how accurate this software emulation of the SID chip is

I won't be able to tell you until I hear "California Girls" on it. Not sure where I left the copy of Byte or whatever magazine that had the program for it.
posted by yerfatma at 8:46 AM on February 21


Awesome! Can I play Karateka now?
posted by mintcake! at 9:21 AM on February 21


Yay me! I made the theme to the inception trailers ....
BWAAAAHM .... BWAAAAHM ... BWAAAHM ...
posted by forforf at 10:09 AM on February 21


Does not sound terribly SID-like, sadly (and unsurprisingly).

Chipsounds is a seriously good emulation though.
posted by Foosnark at 10:21 AM on February 21


Foosnark, I'll have to check that out. I'm a big fan of quadraSID myself. I even used it on this old Music post.
posted by hellphish at 10:34 AM on February 21 [1 favorite]


This is wonderfully grungy.
posted by swift at 10:47 AM on February 21


SID synths are relatively popular. As mentioned above (and a few more) Chipsounds, HardSID, QuadraSID, SIDizer are a few commercial offers.

Of course you could also go FULL HARDCORE and get the MSSIAH (note: requires an actuall Commodore 64).

Here it is in action.
posted by Doleful Creature at 10:54 AM on February 21 [1 favorite]


@Doleful, don't forget the SidStation, the OG of SID synths.
posted by grumpybear69 at 11:17 AM on February 21 [2 favorites]


Many years ago I wrote a sound effect generator for the C64. I remember hardly anything about it now, though.
posted by JHarris at 12:15 PM on February 21


I was just recently listening to music from the Last Ninja series.

People have made some pretty wicked music with the C64.
posted by Redfield at 12:24 PM on February 21 [1 favorite]


Anyone know how the C64 managed to get 8+ note polyphony with only 3 wave generators? Did they just rotate between them really fast?

Back in the day I remember it was always the sound chip that got blown out whenever we got a power surge from a thunderstorm. Must have replaced it 3 or 4 times.
posted by crapmatic at 12:25 PM on February 21


Back in the day I remember it was always the sound chip that got blown out whenever we got a power surge from a thunderstorm. Must have replaced it 3 or 4 times.

The NMOS logics based 6581 SID was, like all MOSFET based chips, extremely susceptible to static electricity. The HMOS-II logic 8580 SID was more tolerant to overload, and ran on 9VDC, rather than 12VDC, the two in combination made the 8580 SID vastly more reliable.

Much like tube amps, though, the flaws in the 6581 made it the more popular chip for music.
posted by eriko at 12:37 PM on February 21 [3 favorites]


Crapmatic: what you're thinking of is probably the Skate Or Die theme song and its ilk. Those tunes used the click generated by modulating the master volume to create a fourth channel which could be used for low-sample-rate sample playback. Same technique was used for Impossible Mission's "destroy him my robots" sample.
posted by grumpybear69 at 3:27 PM on February 21


I'd answer your question, Crapmatic, but I was only ever an intermediate-level SID synther. You can do interesting things, though, by switching between sounds rapidly of course, but also if you plan out your composition so that only three notes ever play at once.

The technique grumpybear69 suggests works. I found a type-in program from the letters column of what I think it was an issue of Ahoy! that used a short machine code loop to play audio cassettes off the Datasette input peripheral by clicking the volume directly based on what was coming in from the data port. The output was pretty horrible (the letter mentioned "the fidelity isn't good"), but it was still recognizable.
posted by JHarris at 3:43 PM on February 21


They ran ICs on 12V DC back then? The past is indeed a strange country.
posted by acb at 3:46 PM on February 21


Does not sound terribly SID-like, sadly (and unsurprisingly).

True. "No samples were used it's all math" suggests some corner-cutting was needed. BUT the real message here is that the new WebAudio API, along with the amazing gains in JS speed, are bringing endless possibities for all. No 4MHz chip and ASM code needed any more. I'm jazzed.
posted by Twang at 4:55 PM on February 21 [1 favorite]



I'd answer your question, Crapmatic, but I was only ever an intermediate-level SID synther. You can do interesting things, though, by switching between sounds rapidly of course, but also if you plan out your composition so that only three notes ever play at once.

The technique grumpybear69 suggests works. I found a type-in program from the letters column of what I think it was an issue of Ahoy! that used a short machine code loop to play audio cassettes off the Datasette input peripheral by clicking the volume directly based on what was coming in from the data port. The output was pretty horrible (the letter mentioned "the fidelity isn't good"), but it was still recognizable.


I came across Cybernoid II by Jeroen Tel last week (on Spotify!). I was listening to it and I just couldn't wrap my head around the fact that this was using only three channels. Sure, there are a lot of very fast arpeggios and the song is indeed constructed so that the melody, accents and drums are alternating nicely - yet I still believe there's a hint of magic in there.

Is there an archive of "readable" SID songs out there? I can only find recreations (with more channels), but I'd love to see the original song/arrangement.
posted by swordfishtrombones at 6:28 AM on February 22


They ran ICs on 12V DC back then? The past is indeed a strange country.

The SID was a mixed analogue/digital IC, not pure digital. It used that 12VDC in many ways, including converting part of it into AC on-chip.

The C64 power supply system was many things*. It started with the power brick**. A two tap transformer fed out two outputs. The first, at about 7VAC, was sent to a linear regulator***, which output 5VDC at 2A. The other tap sent 9VAC out. Total output was 2A@5VDC, 1A@9VAC..

The 5VDC drove the computer. The 9VAC was used for many things. First, every time the AC wave peaked above 0, it stepped the Time of Day clock. Yes, like many AC powered clocks, they used the power frequency as a stable 60Hz (NTSC) or 50Hz (PAL, etc.) frequency reference. Secondly, it fed a charge pump and regulator that output 12VDC for the SID. Third, it was pinned directly to the user port, where a certain class of external devices could use it.††

Finally, it was run through a bridge rectifier, the unregulated DC that came out, about 6.3VDC, was used to drive the tape motor if you had the tape drive connected.



* Large, failure prone, heavy, hot, complicated….

** Which was heavy, hot, and potted in epoxy so you couldn't fix it. If someone offers you a dead C64, what they're probably offering you is a perfectly good C64 with a dead power brick.

*** AKA "Heat emitting piece of crap" -- linear regulators work well (7805, anybody?) but they dump the excess power as heat. Then, imaging potting your linear regulator. Output? 2 amps. This decision is the biggest reason why C64 power bricks failed. They did keep your feet warm****, though, so it's not *all* bad.

**** In my case, by attracting a cat. How not to cool a C64 power brick -- drape a cat around it.

† This makes it actually quite easy to bodge up a new C64 power supply. 5VDC@2A is not impossible to find, and 1A@9VAC is easy -- look for any USR modem power supply. You really want a little more DC, but if you can drive a 2.5A 5VDC and a 1A9VAC power wart, you can feed those into a C64 and get a vastly better power supply.

†† Hint: Where did I tell you to get a 9VAC wall wart from?
posted by eriko at 7:32 AM on February 22 [2 favorites]


Those tunes used the click generated by modulating the master volume to create a fourth channel which could be used for low-sample-rate sample playback.

The reason for the click was the flawed design of the 6581 SID. It put a DC bias on the sound output. The trick here is the bias depended on the master volume -- the higher it was set, the bigger the DC offset.

So, if you switched the master volume quickly, you were in effect generating pulses. Do that fast enough, and you're playing back samples. Change the channel volumes in inverse, at the same time, and you're playing a sample *and* three SID voices at the same time.

This, btw, took a lot of CPU, which is why you heard it used on demos and intro screens, but not actually when you were playing a game.

On the 8580 SID, they fixed the offset. This, of course, broke the trick -- but then again, when you exploit a bug, you get burned when the bug is fixed. There were people who, by soldering in a resistor and capacitor onto the Audio IN pin, would put the DC bias back in on an 8580 SID output. We called this "bug compatible patching." You could make the trick work without hardware mods, but it took a SID voice away doing it. Of course, just like chords, if you switched fast enough, you could hide the fact.
posted by eriko at 2:22 PM on February 22 [1 favorite]


> They ran ICs on 12V DC back then? The past is indeed a strange country.

Answered by eriko (oh, what an answer!), but earlier ICs required all kinds of things. The Intel 8080 required +5, -5 and 12V. It also needed a clock generator and bus controller. The Motorola 6800 also needed 3 power supplies, but generated them on-chip. It wasn't until the Mostek 6502, Zilog Z80 and Intel 8085 (2 years too late) that you could run from a single-phase clock and 5 Volts. Intel & Motorola kind of lost out to the upstarts.
posted by morganw at 4:16 PM on February 22 [1 favorite]


but earlier ICs required all kinds of things.

Well, most op-amps require +VDC and -VDC, but yeah, it used to be a wilder world -- anything dealing with RS-232 serial was supposed to have +10VDC, but that was honored most often by the breach.
posted by eriko at 5:07 PM on February 22


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