SN76477NF Voice IC

SN76477 Voice IC

"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.

— Lou Garner, Solid State, Popular Electronics magazine, October 1978"

The SN76477NF, the smaller of the two available DIP packages is 0.4" wide with pin spacing = 0.07 per the datasheet. 

The other DIP package is SN76477N which is 0.6" wide with pin spacing 0.1 per the datasheet. 

The chips are functionally identical.