The quoted tweet shows what appears to the guts of a PDP-8/I, circa 1968, a TTL based machine. The original PDP-8, circa 1965, was larger and used discrete transistor logic.
The mass of circuit boards that was an original PDP-8 minicomputer from the 1960s was replaced with a single IC - the HD6120 - in 1981. Today you can run a faithful PDP-8 emulation on a Raspberry Pi 3 without breaking a sweat :) (apart from finding a Pi in stock).