The PDP-7 is an

18-bit Eighteen binary digits have 262,144 (1000000 octal, 40000 hexadecimal) distinct combinations. Eighteen bits was a common word size for smaller computers in the 1960s, when large computers often using 36 bit words and 6-bit character sets, som ...

minicomputer A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...

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 until ...

as part of the

PDP PDP may refer to: Computing and technology * Packet Data Protocol in wireless GPRS/HSDPA networks * Parallel distributed processing in Connectionism#Parallel distributed processing, connectionism * Plasma display panel * Policy Decision Point in t ...

series. Introduced in 1964, shipped since 1965, it was the first to use their

Flip-Chip Flip chip, also known as controlled collapse chip connection or its abbreviation, C4, is a method for interconnecting Die (integrated circuit), dies such as semiconductor devices, Integrated circuit, IC chips, integrated passive devices and micr ...

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) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. A device or program that executes instructions described by that ISA, ...

as the

PDP-4 The PDP-4 was the successor to the Digital Equipment Corporation's PDP-1. History This 18-bit machine, first shipped in 1962, was a compromise: "with slower memory and different packaging" than the PDP-1, but priced at $65,000 - less than half t ...

and the

PDP-9 The PDP-9, the fourth of the five 18-bit minicomputers produced by Digital Equipment Corporation, was introduced in 1966. A total of 445 PDP-9 systems were produced, of which 40 were the compact, low-cost PDP-9/L units.. History The 18-bit PDP ...

Hardware

The PDP-7 was the first

wire-wrapped Close-up of a wire-wrap connection Typical wire wrap construction of crossbar_switch.html" ;"title="Bell System telephone crossbar switch">Bell System telephone crossbar switch. Some types of connection were soldered. Wire wrap is an electron ...

PDP computer. The computer has a memory cycle time of and an add time of .

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

(I/O) includes a keyboard, printer,

punched tape file:PaperTapes-5and8Hole.jpg, Five- and eight-hole wide punched paper tape file:Harwell-dekatron-witch-10.jpg, Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program ...

and dual transport

DECtape DECtape, originally called Microtape, is a magnetic tape data storage medium used with many Digital Equipment Corporation computers, including the PDP-6, PDP-8, LINC-8, PDP-9, PDP-10, PDP-11, PDP-12, and the PDP-15. On DEC's 32-bit systems, VAX ...

drives (type 555). The standard

core memory Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber), ...

capacity is but expandable up to The PDP-7 weighs 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 provides an interactive, single user, program development environment for Fortran and

assembly language In computing, assembly language (alternatively 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 bet ...

programs. In 1969,

Ken Thompson Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B (programmi ...

wrote the first

UNIX Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user 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, a ...

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 t ...

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 Gen ...

at MGH in

Boston Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...

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 ; ) 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 1,064,235 in 2022 ...

, 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 university, public research university in Eugene, Oregon, United States. Founded in 1876, the university is organized into nine colleges and schools and offers 420 undergraduate and gra ...

in its Nuclear Physics laboratory is now at the

Living Computer Museum Living Computers: Museum + Labs (LCM+L) was a computer and technology museum located in the SoDo neighborhood of Seattle, Washington. LCM+L showcased vintage computers which provided interactive sessions, either through time-sharing operating ...

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 computer museum in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the Information Age, and explores the Digital Revolution, computing revolution and its impact ...

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