The 801 started as a pure research project led by John Cocke at the Thomas J. Watson Research Center in building 801. They were looking for ways to improve performance of their existing machines, studying traces of programs running on IBM 370 mainframes and looking at the compiler code. From this project led the idea that it was possible to make a very small and very fast core, which could then be used to implement the microcode for any machine.
The project then moved on to produce the design as a CPU, also called the 801. The resulting CPU was produced in 1977 running at the then-fast speed of 15 MIPS. It was used in a variety of IBM devices including channel controllers for their 370 mainframes, various networking devices, and eventually the 9370 mainframe core itself.
In the early 1980's the lessons learned on the 801 were put back into the new America Project, which led to the IBM POWER architechture.
John Cocke later won both the Turing award and the Presidential Medal of Technology for his work on the 801.