The PDP-7 was a

minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ' ...

produced by

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president un ...

as part of the PDP series. Introduced in 1964, shipped since 1965, it was the first to use their Flip-Chip technology. With a cost of , it was cheap but powerful by the standards of the time. The PDP-7 is the third of Digital's 18-bit machines, with essentially the same

instruction set architecture In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ...

as the PDP-4 and the PDP-9.

Hardware

The PDP-7 was the first wire-wrapped PDP computer. The computer had a memory cycle time of and an add time of .

Input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...

(I/O) included a keyboard, printer,

punched tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

and dual transport DECtape drives (type 555). The standard core memory capacity was but expandable up to The PDP-7 weighed about .

Software

DECsys, the first operating system for DEC's 18-bit computer family (and DEC's first operating system for a computer smaller than its 36-bit timesharing systems), was introduced in 1965. It provided an interactive, single user, program development environment for Fortran and

assembly language In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence b ...

programs. In 1969, Ken Thompson wrote the first

UNIX Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...

system, then named Unics as a pun on

Multics Multics ("Multiplexed Information and Computing Service") is an influential early time-sharing operating system based on the concept of a single-level memory.Dennis M. Ritchie, "The Evolution of the Unix Time-sharing System", Communications of ...

despite only using two design elements from Multics, in assembly language on a PDP-7, as the operating system for '' Space Travel'', a game which requires graphics to depict the motion of the planets. A PDP-7 was also the development system used during the development of

MUMPS MUMPS ("Massachusetts General Hospital Utility Multi-Programming System"), or M, is an imperative, high-level programming language with an integrated transaction processing key–value database. It was originally developed at Massachusetts Gene ...

at MGH in

Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...

a few years earlier.

Sales

The PDP-7 was described as "highly successful." A combined total of 120 of the PDP-7 and PDP-7A were sold. A DEC publication states that the first units shipped to customers in November 1964. Eleven systems were shipped to the UK.

Restorations

At least four PDP-7s were confirmed to still exist as of 2011 and a fifth was discovered in 2017. A PDP-7A (serial number 115) was under restoration in

Oslo Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of ...

, Norway; a second PDP-7A (serial number 113) previously located at the

University of Oregon The University of Oregon (UO, U of O or Oregon) is a public research university in Eugene, Oregon. Founded in 1876, the institution is well known for its strong ties to the sports apparel and marketing firm Nike, Inc Nike, Inc. ( or ) is a ...

in its Nuclear Physics laboratory is now at the Living Computer Museum in Seattle, Washington and is completely restored to running condition after being disassembled for transport; University of Oregon's PDP-7 moves to the Living Computer Museum in Seattle, Washington. Alternate host at https://www.soemtron.org/pdp7no113systeminfo.html "January 2011" section. Another PDP-7 (serial number 47) is known to be in the collection of Max Burnet near Sydney, Australia, a fourth PDP-7 (serial number 33) is in storage at the

Computer History Museum The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact o ...

in Mountain View, California and a fifth PDP-7 (serial number 129) belonging to Fred Yerian is also located at the Museum, and has been demonstrated running Unix version 0 and compiling a B program.

References

External links

Information about the PDP-7 and PDP-7/A
including some manuals and a customer list covering 99 of the systems shipped, Digital Equipment Corporation PDP-7. * {{DEC hardware DEC minicomputers Transistorized computers 18-bit computers Computer-related introductions in 1965 Products introduced in 1965