Inside an IBM/Motorola mainframe controller chip from 1981

In this article, I look inside a chip in the IBM 3274 Control Unit.1 But before I discuss the chip, I need to give some background on mainframes.
↫ Ken Shirriff

Whenever we talk about mainframes, I am obligated to link to the story of an 18 year old buying a mainframe, while still living at his parents. One of the greatest presentations of all time.