[ datasheet ]
[ programmer ]
[ instruction set ]
[ red cedar technical page ]
[ apple II mockingboard info ]

All the SC-01a did was to synthesize 64 phonemes (done in a time when ROM was expensive). It has two control bits that made simple variations on the 64 thus creating 256 somewhat different sounds. On the Gottlieb system the SC-01a was further elaborated by utilizing a DAC to control the clock for the SC-01a thus controlling the sampling rate (pitch and length) of the results. This was used to good effect in Q*Bert to create the different voices.

The SC-01A doesn't just concatenate - there's smoothing going on. The datasheet for the SC-01A doesn't go into the details, however the patents by Richard Gagnon and others for the various Votrax speech devices will tell you more than you want.

A few Gagnon/Federal Screw Works ("Votrax") patents:

3836717, 1974
3908085, 1975
4128737, 1978
130730, 1978

The first two are probably the discrete implementations that preceded the SC-01; while the last two are probably the SC-01. First two will tell you more about how Richard Gagnon did it.

Upping the clock rate moves the pitch up, and speeds up overall timing. There are also two inputs for selecting 4 different pitches (w/o changing timing, presumably). The clock can be an RC, and they show a pot allowing for adjustable pitch.

[ back ]