Just happened to see one on an ancient rerun of the "Patty Duke
Show".
Although it was a "training computer", it still had 512 words of 15-
bit storage and an instruction repertoire of 61 instructions. (6 bit
opcode+9 bit address). Ed Thelen's list gives it as 1963.
Power consumption, from the manufacturer's brochure, was 500W, with a
115VAC supply. Thelen gives it as 1.13KW, but I suspect that the
difference is in the I/O device (typewriter, paper tape punch).
Given the modest space and power requirements, would the 422 qualify
as another one of the first minicomputers?
Cheers,
Chuck