Groups comparison

Covox Speech Thing SPU - 1988 to 1996
An extremely primitive & cheap dongle that plugged into a parallel port to provide 8-bit DAC digital sound output that was superior to the PC speaker.

Covox Sound Master - 1989 to 1996

Covox Voice Master SPU - 1989 to 1996
This is an ISA version of the Speech Thing that has similar ability but also DMA. Play back of sound stored on the card did not waste CPU bandwidth.

Intersound MDO SPU - 1989 to 1991
An improved and non-compatible clone of the Covox Speech Thing.

Disney Sound Source - 1990 to 1996
An improved and not exactly compatible clone of the Covox Speech Thing packaged with an external speaker.