Chip64 is a synth that emulates sound chips from early computers and video game consoles. It does not use samples, but rather mathematically models the entire dynamic range of each wave of each chip. This makes Chip64 very fast, very accurate, and light on DSP.
SN76489 (used in the Colecovision and Sega consoles)
Chip64 comes with its own onboard sequencer, allowing free-running and tempo-synced sequences of up to 4 notes, looped and one-shot. Additionally, each iteration of the loop can be offset by any number of half-steps up to a full octave up or down.
There’s an extremely aggressive multi-mode bi-quad filter included, featuring low pass, high pass, band pass, notch, parametric, low shelf, and high shelf modes. The frequency range for each filter is the entire audible range, and the slope goes from 0 to infinity, allowing for everything from surgical cuts and boosts to gentle effects over the entire frequency range. Each filter can also be overdriven leading to self-oscillation.
Notes can be tuned up and down four octaves, up and down 12 notes, and up and down 100 cents.
Can be either monophonic or polyphonic, with voice counts from 1 to 12.
Pulse width (used with the SID pulse wave)
ADSR envelope with attack, decay, and release times from 0 to 2 seconds
LFO with seven waveforms (sine, triangle, ramp, reverse ramp, square, exponential) that can be sent to eight different destinations (pitch, volume, filter frequency, filter gain, filter Q, sequence offset, sequence rate, pulse width)
LFO can be free-running or tempo synced and can scale from off to full amplitude.
Pitch bend with range from 1 to 12 steps.
Modulation wheel with scale from -100% to 100% that can be sent to seven destinations (filter frequency, filter gain, filter Q, LFO rate, LFO scale, pulse width, sequence rate).
Modulation envelope with scale from -100% to 100% that can be sent to nine destinations (pitch, filter frequency, filter gain, filter Q, volume, LFO rate, LFO scale, pulse width, sequence rate).
Oversample settings (off, low, high).
Stereo audio in.
CV connections for gate and note out.
CV connections for sequence gate and note out.
CV connections for LFO and Modulation envelope out.
CV connections for gate and note in.
CV connection for envelope in.
Four generic CV ins that can be sent to 12 destinations (pitch, volume, filter frequency, filter gain, filter Q, sequence offset, LFO rate, LFO scale, pitch bend wheel, mod wheel, pulse width, sequence rate).
Many online resources were used during the making of Chip64. The online community of chip emulation enthusiasts is vast, and their willingness to share information is impressive. Without them, Chip64 may not have been possible. Special thanks to C3 Emulation, Commodore.ca, AtariAge, Mame Dev, Plogue, John Kortink, SMS Power, Paul Slocum, and many many more.