Texas Instruments SN76477

SN76477 "complex sound generator" was a sound chip produced by Texas Instruments (TI). The chip came to market in 1978, and TI production of the part ceased some time ago. More recently, a 100% compatible version, identified as ICS76477, has been listed as 'in stock' by at least one US-based component stockist. The chip was 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 was limited by the fact that it was difficult to electronically control the pitch of the produced sound.

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, 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.

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 bottom right.

Uses of the SN76477 include the following devices:

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