Commodore C64 Modifications
By: AlphA
modifications in red

About the SID.

SID 8580R5
SID 8580R5

The SID chip first appeared in Commodoreís C64 home computer system. Since its debut, the SID chip has been the heart of many music machine projects. Even today, many of these projects are ongoing while new uses for the SID continue to surface despite the fact that is has been out of production for years. One of the more popular SID innovations is Prophet64. Prophet64 is a suite of user friendly music applications for the Commodore 64 platform. This pioneering work allows the SID to integrate into a professional studio without leaving its original home inside the C64 computer. I find it ironic that it took until the twenty first century for a 1980ís piece of hardware to finally merge with modern music applications.

There is a wealth of information about the SID available on the web for those of you who really want to learn all about it. Basically, it is an analog synthesizer packed into a single integrated circuit with impressive specifications, such as three tone oscillators each comprising four waveforms (triangle, sawtooth, variable pulse, pseudo-random noise) and dedicated amplitude modulators, three 4-stage (attack, decay, sustain, release) envelope generators, oscillator synchronization, ring modulation, 12db multimode (high, low, band pass) variable resonant analog filter, external audio input (processed through filter or directly mixed with output), and an immense array of patchability limited only by the imagination of the program developer. This is an astonishing amount of flexibility for an integrated circuit created twenty years ago. For the musician, itís like using a VST without sinning against the analog gods (pretty neat for us vintage analog purists).

Since the C64 is an 8-Bit system, and the SID is controlled by 8-bit values generated by the C64, it has gained popularity among a community of musicians who utilize 8-bit technology in order to create music with sounds reminiscent of 1980's video games (8-Bit Music). However, the sound of the SID chip is far from limited to bleeps and blips.

In 2006, Prophet64 made the bold move of releasing its SID music software on C64 cartridges. This completed the C64's transition from computer system dependant on floppy and/or tape drives, to an independent piece of pro audio studio equipment. Could the union of Prophet64 with the C64 as a musical instrument be further improved upon? I thought so. The following pages explain what I have done.

If you decide to perform these mods to your C64, I recommend that you do so one at a time, stopping to test each mod as you progress. Itís also a good idea to do them in order. You donít want to create a difficult situation, such as removing the original video connector before you have the S-video mod working.

As usual ďIím not responsible if you blow your stuff upÖ blah blah blah (disclaimer stuff)." Just donít be stupid and donít blame me. :)






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