PDP-7
| Company type | Public |
|---|---|
| Industry | Computer hardware |
| Founded | May 16, 1957 in Massachusetts, United States |
| Headquarters | Maynard , United States |
| Products | PDP-7 minicomputer |
The PDP-7 is an 18-bit minicomputer developed by Digital Equipment Corporation as a member of the PDP lineup. Launched in 1964 and delivered starting in 1965, it marked the debut of DEC's Flip-Chip technology. With a price tag of , the PDP-7 provided an affordable yet capable computing option for its era. It represents Digital's third 18-bit system and shares a closely related instruction set architecture with both the PDP-4 and PDP-9 models.
Hardware
The PDP-7 was notable as the first PDP computer to utilize wire-wrapping techniques, boasting a memory cycle duration of 1.75 microseconds and an addition operation time of 4 microseconds. Its input/output configuration supported devices such as a keyboard, printer, punched tape reader, and dual DECtape drives (model 555). The machine came standard with 4K words (equivalent to 9 KB) of core memory, expandable up to 64K words (144 KB). The total weight of the PDP-7 was around 1100 pounds (500 kilograms).
Software
Introduced in 1965, DECsys was Digital's inaugural operating system tailored for its 18-bit and smaller computers, delivering an interactive, single-user platform for programming in Fortran and assembly language.
In 1969, Ken Thompson created the initial UNIX operating system—originally called Unics as a play on the name Multics—incorporating only two concepts from Multics. Developed entirely in assembly language on a PDP-7, UNIX functioned as the OS for Space Travel, a graphical game simulating planetary orbits. Earlier, the PDP-7 had also been employed at Massachusetts General Hospital during the development of the MUMPS programming language.
Sales
The PDP-7 achieved what was described as "considerable success." In total, 120 units combining both PDP-7 and PDP-7A models were sold, with initial deliveries to clients beginning in November 1964. Of these, eleven systems were supplied to customers in the United Kingdom.
Restorations
As of 2011, at least four PDP-7 machines were known to be preserved, with a fifth unit identified in 2017. Significant restoration efforts include a PDP-7A (serial number 115) located in Oslo, Norway, and another unit (serial number 113) transferred from the University of Oregon to Seattle’s Living Computer Museum, where it has been fully restored and is operational. Additional examples are held by private collectors and institutions: serial number 47 near Sydney, Australia; and serials 33 and 129 housed at the Computer History Museum in Mountain View, California—the latter demonstrated running Unix version 0 and compiling a B programming language application.