2 Fundamentals

UNIX runs on the larger models of the PDP11 series of computers manufactured by Digital Equipment Corporation. This chapter provides a brief summary of certain selected features of these computers with particular reference to the PDP11/40.

If the reader has not previously made the acquaintance of the PDP11 series then he is directed forthwith to the “PDP11 Processor Handbook”, published by DEC.

A PDP11 computer consists of a processor (also called a CPU connected to one or more memory storage units and peripheral controllers via a bidirectional parallel communication line called the “Unibus”.