SN76477 "complex sound generator" is a sound chip produced by Texas Instruments (TI). The chip came to market in 1978,[1] and TI ceased production of the part.[when?] A compatible version is identified as ICS76477.[2] The chip is typically used as a sound effects generator in arcade games and toys and for hobby projects. The use of the SN76477 in a musical context is limited by the fact that it was difficult to electronically control the pitch of the produced sound.[3]
The following quotation summarizes its facilities:
[T]he SN76477 generates complex audio signal waveforms by combining the outputs of a low frequency oscillator, variable frequency (voltage controlled) oscillator (VCO) and noise source, modulating the resulting composite signal with a selected envelope and, finally, adjusting the signal's attack and decay periods. At each stage, the process can be controlled at the programming inputs of the signal modification and generation circuits, using control voltages, logic levels, or different resistor and capacitor values.
— Lou Garner, Solid State, Popular Electronics magazine, October 1978.[4]
There were two different sizes of the SN76477 available. The SN76477N was in a standard 0.6 in (15.24 mm) width dual in-line package (DIP). The SN76477NF was in a less common 0.4 inch (10.16 mm) width DIP.
The text below is intended to explain the use of the 76477 in the demo circuit shown at the right.
Redraws of 76477 application circuits;
Uses of the SN76477 include the following devices:
