PDP-10

The PDP-10 was a mainframe computer family manufactured by Digital Equipment Corporation (DEC) from 1966 into the 1980s. Although the Jupiter project would have delivered an improved version for sales during the mid-to-late 1980s, DEC instead replaced the PDP-10 with models of the VAX series.

The PDP-10 architecture was an almost identical version of the earlier PDP-6 architecture, sharing the same 36-bit word length and slightly extending the instruction set (but with improved hardware implementation). Some aspects of the instruction set are unique, most notably the "byte" instructions, which operated on bit fields of any size from 1 to 36 bits inclusive according to the general definition of a byte as a contiguous sequence of a fixed number of bits.

The PDP-10 was the machine that made time-sharing common, and this and other features made it a common fixture in many university computing facilities and research labs during the 1970s, the most notable were MIT's AI Lab and Project MAC, Stanford's SAIL, Computer Center Corporation (CCC), and Carnegie Mellon University. . Its main operating systems, TOPS-10 and TENEX, were used to build out the early ARPANET. For these reasons the PDP-10 looms large in hacker folklore.