MOS Technology SID

The MOS Technology 6581/8580 or SID (Sound Interface Device) is the built-in Programmable Sound Generator chip used in the Commodore 64 and Commodore 128 home computers in the 1980s.

Development
The SID was devised by engineer Robert "Bob" Yannes, who later co-founded the Ensoniq Corporation.

Let the buyer beware
Since 6581 and 8580 SID ICs are no longer produced, they have become highly sought after. In late 2007, various defective remarked SIDs started appearing on eBay as supposedly new chips. All of these remarked SIDs have a defective filter, but some also have defective channels/noise generators, and some are completely dead.

SID chip versions
The first version was the 6581 followed by the 8580, (in the later flat grey Commodore C64C). The 6582 was sold as replacement for defective 8580s, and sounds very similar. The main difference is the supply voltage and filter caps. The 6581 takes 12V and requires 470pF caps while the 8580 and 6582 take 9V and require 22nF caps.

There are also sound differences. The filter of the 6581 sounds more moody and dirty, while the 8580/6582 filter sounds more precisely. Resonance has nearly no effect on the 6581, some mixed waveforms are not working, and it has a much higher background noise. The 8580/6582 is normally the preferred choice.

See also SID sound comparison.

Hardware emulation
The SwinSID is designed to be a pin compatible replacement module for both versions of the SID IC. Based on the Atmel AVR microcontroller It does not sound exactlty the same as either of the original ICs.

Projects

 * MIDIbox SID V2
 * SIDblaster
 * HyperSID
 * Atmel ATmega168 MOS 6581 SID Player
 * Interfacing a SID to the ATmega

Modules

 * ALM003 – SID GUTS