Brent H. wrote:
An almost identical system was used for the backplane wiring on many
Wang Laboratories electronic calculators, from the earliest machines
(LOCI) through the last of the "large form factor" machines (Wang
500/600/700) calculators. Later machines (100, 400 and C-Series) had
much higher levels of integration, which required a lot fewer backplane
interconnects, and thus printed circuit backplanes could be used.
The Old Calculator Museum