Thompson and Ritchie were among the first to realize that hardware and compiler technology had become good enough that an entire operating system could be written in C, and by 1978 the whole environment had been successfully ported to several machines of different types.

The workstation-class machines built by Sun and others opened up new worlds for hackers.

If Unix could present the same face, the same capabilities, on machines of many different types, it could serve as a common software environment for all of them.

Eric S. Raymond Quotes