Re: Mini computer
I suppose the gold standard for a minicomputer in the 70s was the DEC PDP series. These were closest in general architecture to early microprocessor systems, being based around a backplane with plug-in cards. The systems had up to 256Kwords of 16 bit memory and probably clocked no faster than 25MHz. A Pi-Zero would wipe the floor with one.
As an aside I worked at a company in the late 80s had a VAX (that's the 32 bit DEC mini). This system originally managed terminals but had became the server for our desktop PCs. It was replaced one day with a PC, a 386 system. The result was sad -- where once a bustling system with chattering chain printer stood in its dedicated environment with individual A/C and raised floors -- a proper computer room -- was now a dark, empty, alcove with a single PC sitting in the corner.