CONCEPT
The 6581 Sound Interface Device (SID) is a single-chip, 3-voice electronic
music synthesizer/sound effects generator compatible with the 65XX and similar
microprocessor families. SID provides wide-range, high-resolution control
of pitch (frequency), tone color (harmonic content), and dynamics (volume).
Specialized control circuitry minimizes software overhead, facilitating
use in arcade/home video games and low-cost musical instruments.
FEATURES
- 3 TONE OSCILLATORS
Range: 0-4 kHz
- 4 WAVEFORMS PER OSCILLATOR
Triangle, Sawtooth, Variable Pulse, Noise
- 3 AMPLITUDE MODULATORS
Range: 48 dB
- 3 ENVELOPE GENERATORS
Exponential response
Attack Rate: 2 ms - 8 s
Decay Rate: 6 ms - 24 s
Sustain Level: 0 - peak volume
Release Rate: 6 ms - 24 s
- OSCILLATOR SYNCHRONIZATION
- RING MODULATION
- PROGRAMMABLE FILTER
Cutoff range: 30 Hz - 12 kHz
12 dB/octave Rolloff
Low pass, Bandpass,High pass, Notch outputs
Variable Resonance
- MASTER VOLUME CONTROL
- 2 A/D POT INTERFACES
- RANDOM NUMBER/MODULATION GENERATOR
- EXTERNAL AUDIO INPUT
DESCRIPTION
The 6581 consists of three synthesizer "voices" which can be used
independently or in conjunction with each other (or external audiosources)
to create complex sounds.
Each voice consists of a tone oscillator/waveform generator,an envelope
generator and an amplitudemodulator.
The tone oscillator produces four waveforms at the selected frequency, with
the unique harmonic content of each waveform providing simple control of
tone color. The volume dynamics of the oscillator are controlled by the
amplitude modulator under the direction of the envelope generator. When
triggered, the envelope generator creates an amplitude envelope with programmable
rates of increasing and decreasing volume.
In addition to the three voices, a programmable filter is provided for generating
complex, dynamic tone colors via subtractive synthesis.
Please note that the SID is not a FM-based synthesizer, like the Yamaha
OPL series !!
SID allows the microprocessor to read the changing output of the third oscillator
and third envelope generator. These outpus can be used as a source of modulation
information for creating vibrato, frequency/filter sweeps and similar effects.
Two A/D converters are provided for interfacing SID with potentiometers.
These can be used for "paddles" in a game environment or as front
panel controls in a music synthesizer. SID can process external audio signals,
allowing multiple SID chips to be daisy-chained or mixed in complex polyphonic
systems.