::|CONTENTS
- Specifications
- Competition
- Tools
- See also
The sound produced by the SID microchip is one of the most well-know sounds in chip music due to the popularity of the consoles that had it implemented.
Specifications
The MOS Technology 6581/8580 SID (Sound Interface Device) was the built-in Programmable Sound Generator chip of Commodore's
CBM-II,
Commodore 64,
Commodore 128 and Commodore
MAX Machine home computers. The SID is a mixed-signal integrated circuit, featuring both digital and analog circuitry. All control ports are digital, while the output ports are analog.
The sound chip, SID, had three channels, each with its own ADSR envelope generator, and with several different waveforms, ring modulation and filter capabilities.
Each voice may use one of at least five different waveforms:
- square wave (with variable duty cycle),
- triangle wave,
- sawtooth wave,
- pseudo-random (but not white) noise, and
- certain complex/combined waveforms.
Each voice may be ring-modulated with one of the other voices, i.e. the frequency spectrum is convolved and output. The ring modulation, filter, and programming techniques for switching between different waveforms at high speed make up the characteristic sound of the SID.
Each voice may be passed through a common, digitally controlled analog filter with variable cut-off frequency and resonance, which is constructed with the aid of capacitors external to the circuit. An external audio in port enables external audio to be passed through the filter.
Versions
There are two versions of the SID chip. The first version was the MOS Technology
6581, which is to be found in all of the original "breadbox"
C64s, and early versions of the
C64C and the
Commodore 128. It was later replaced with the MOS Technology
8580 in 1987. The sound quality was a little more crisp on the
6581 and many
Commodore 64 fans still prefer its sound.
The main difference between the
6581 and the
8580 was the voltage supply: the
6581 uses a 12 volt supply, while the
8580 required only 9 volts. A voltage modification can be made to use a
6581 in a C64C board (which uses 9V).
Competition
-
sid (format)
Tools
See
sid (format)
See also
-
Commodore 64
-
Commodore 128
-
MAX Machine
-
sid (format)
