[Editor's Note: This two-part series fell into my lap rather serendipitously. I reached out to Jeremy W. Kaufmann, who you may know as the host of the hilarious Destroy All Podcasts DX show, as he dabbles in the chiptunes world with I'm Insincere and Violence Mars (he's also one of the creators of the upcoming Homeless Dinosaur comic). He replied with a pair of epic e-mails that were so chock full of goodness that I decided to use them more of less in their entirety. I now turn you over to Jeremy for some technical background on the C64's sound chip.]
Warning: This is really fucking long. Another warning: I heavily favor the Commodore 64, because when I started out, I was using an actual C-64.
COMMODORE 64: THE ADVANTAGES
The C-64 has its advantages–you can program it directly using BASIC, assembly, or machine language, and you can use old C-64 music creation software. Some of that software even lets you play it in real time as if it were a music keyboard, but there are some pretty big disadvantages to using a real C-64 as well.
COMMODORE 64: THE DISADVANTAGES
The first problem is getting the sound out of the C-64 into something useful. The real problem is the C-64 is designed to use a TV RF switch adapter, and that is just shit for sound or video. You can use it with a C-64 monitor, but the connection to those is a mono RCA adapter. You know those three colored TV adapters like on a VCR, red, yellow, white? This has just two, red and white. One line is video, one is audio. It kind of sucks, and you still need to adapt that back to something a computer or mixer can use. You can also hack a regular RCA cable to work with the C-64, but it’s not actually real stereo, just faked.
COMMODORE 64: THE SOUND CHIP BREAKDOWN
The C-64′s sound chip, the MOS Technology 6581 SID, is actually really elegant and cleverly designed for the ’80s. Unlike the sound chip in the NES and the Genesis, the SID was custom designed and is actually a subtractive synth, which is an analog/digital hybrid. It’s literally a mixed circuit chip with both digital and analog circuitry. I love it.
I don’t know how into electronic music you are, but analog and digital synthesizers sound pretty different. A famous example of an analog synth is the old school Minimoog. Analogs pretty much always have tubes in them and are expensive to keep going and maintain. Digitals are cheaper and more reliable. Analogs have a warmer, more “human” sound and digitals are colder and more precise. Analogs can actually slip out of tune and have lots of little peculiarities. If you don’t know what I’m talking about, a good example would be analogs are the sounds used in old ’70s prog rock like Pink Floyd (especially Dark Side of the Moon) or whatever and the colder, harsher digitals are frequently used by industrial rock guys like Nine Inch Nails (especially ’90s stuff like The Downward Spiral).
How this relates to the C-64 is that while the SID is a digital chip on a motherboard inside of a computer without tubes or anything, but subtractive synthesis is the method analog synthesizers like the Minimoog generate noises. Wikipedia’s article on subtractive synth explains the concept: Digitals don’t have the same limitations but like the old cliche goes, the limits set you free. You’ll also find that the precision digital offers is not available in analog/subtractive based synths. What I mean in practical terms is when you tell a digital to play an A note, it will hit that note immediately and precisely. If an analog/subtractive is playing a B and you tell it to play an A it does not just jump from the B to the A like it does with digital. There’s actually some degree of “sliding” between notes and depending on what “instrument” you are using, this is more or less pronounced. I love this.
The reason the C-64 rules is you have all the benefits of analog and none of the problems. It won’t slip out of tune, there are no tubes, it’s not likely to break. You can even buy or build synth modules that are just the C-64 SID sound chip chip removed from the C-64 and placed in a dedicated synth module (I’ve seen both MIDI and USB) or even a sound card doing the same you can plug into a PC.
Regarding the analog/digital synth stuff, a lot of that is from experimentation and hearing about it from more experienced musicians. My friend in college had a ’70s Minimoog Voyager he swiped from his old high school teacher and it was always glitchy and liked to slip out of tune.