Back in the 1970s, I worked on the original (or nearly so?) TOW missile system at Emerson Electric in St. Louis. The electronics were composed of a number of encapsulated blocks of (what could be) crumbly black material. These cubes could be thought of as integrated circuits but were actually composed of discrete transistors, resistors, capacitors, etc. inside.

Not as ambitious but I often dealt with building computer systems, including the processor, from the TTL chip level back then. They were still sophisticated, along the lines of what would be called RISC architecture.

You really, really knew how computers and their processors worked back then and God how I miss it.