"The authors have designed and tested a custom n-channel metal-oxide semiconductor (nMOS) chip (the Digitar chip), which computes 16 independent notes, each with a sampling rate of 20 KHz." Kevin Karplus and Alex Strong, "Digital Synthesis of Plucked-String and Drum Timbres", Computer Music Journal, Vol. 7, No. 2 (Summer, 1983), pp. 43-55. That was way more voices than they could get from microprocessors of the day.

In the early 1980's, the big excitement in Stanford EE and CS was that you could take the new VLSI course and they'd actually fab your chip for you if you made it to the end of the course. (Actually, each student project just got a small section of the whole mask; enough chips were manufactured so that everyone could get a few, and they'd just wire the pins to different pads for each particular project's ICs.) I remember Alex showing off his first working Digitar chip to my officemate at the time, Danny Sleator (who is also credited in the paper), using the ice cube technique.