PDP-7

The DEC PDP-7 was a minicomputer produced by Digital Equipment Corporation as part of the PDP series. Introduced in 1965, it was the first to use their Flip-Chip technology. With a cost of only US$72,000, it was cheap but powerful by the standards of the time. The PDP-7 was the third of Digital's 18-bit machines, with essentially the same instruction set architecture as the PDP-4 and the PDP-9. It was the first wire-wrapped PDP. The computer had a memory cycle time of 1.75 µs and add time of 4 µs. I/O included a keyboard, printer, paper-tape and dual transport DECtape drives (type 555). The standard memory capacity was 4K words (9 kB) but expandable up to 64K words (144 kB).

In 1969, Ken Thompson wrote the first UNIX system in assembly language on a PDP-7, then named Unics as a pun on Multics, as the operating system for Space Travel, a game which required graphics to depict the motion of the planets. A PDP-7 was also the development system used during the development of MUMPS at MGH in Boston a few years earlier.