Emerson, Lake & Palmer - Karn Evil 9 3rd Impression

The third Impression deals with the battle of wits and wills between the human and the computer, which will be won by the computer.
Since vocoders were not invented at the time (or just not a thing in the British recording industry), Emerson created the voice for the computer by processing his voice through the ring modulator of his organs.
The band in 1973 was:
Keith Emerson - Hammond B3 & L-100 organs, acoustic and electric pianos, harpsichord, Clavinet, Moog synthesizers, Moog Polyphonic Ensemble (known as the Constellation, comprising the Apollo polyphonic, the Lyra monophonic, and the Taurus Moog bass pedals synthesizers), computer voice (on Karn Evil 9: 3rd Impression)
Greg Lake - vocals, bass, electric and acoustic guitars; production
Carl Palmer - drums, percussion, percussion synthesizers
Peter Sinfield - lyrics