It’s a programmable calculator! Quite large, contains a stack of 5 printed circuit cards, no fewer than 7 custom chips, plus 3 ROM and 4 RAM chips. News item from 1974:
(Photo above from and more technical info at datamath.org.)
Teardown by Dave of EEVblog:
Lots of history and technical info at
The History of Compucorp By Rick Bensene
via hpmuseum forums