PDP-9

The PDP-9, the 4th of the five 18-bit minicomputers produced by Digital Equipment Corporation, was introduced in 1966.[1]:P.10 A total of 445 PDP-9 systems were produced,[2] of which 40 were the compact, low-cost PDP-9/L units.[3]

PDP-9
DEC Logo
DeveloperDigital Equipment Corporation
Product familyProgrammed Data Processor
TypeMinicomputer
Release date1966 (1966)
Units sold445
MediaPaper tape
PlatformDEC 18-bit
Mass750 pounds (340 kg)
PredecessorPDP-7
SuccessorPDP-15

History

The 18-bit PDP systems preceding the PDP-9 were the PDP-1, PDP-4 and PDP-7. Its successor was the PDP-15.

Hardware

The PDP-9, which was "two metres wide and about 75cm deep,"[4] was approximately twice the speed of the PDP-7. It was built using discrete transistors, and had an optional integrated vector graphics terminal. The PDP-9 weighed about 750 pounds (340 kg)[5]:1-7 and the PDP-9/L weighed about 900 pounds (410 kg).[6]

It was DEC's first microprogrammed machine.[7][5]:3-6 through 3-59

A typical configuration included:[2]

Model 33 Teleprinter, similar to the PDP-9's console device, though the PDP-9 had faster dedicated paper tape devices instead of the integrated reader/punch.

Among the improvements of the PDP-9 over its PDP-7 predecessor were:

  • the addition of Status flags for reader and punch errors, thus providing added flexibility and for error detection[8]
  • an entirely new design for multi-level interrupts, called the Automatic Priority Interrupt (API) option
  • a more advanced form of memory management[9]

User/university-based research projects for extending the PDP-9 included:

  • to design a hardware capability for floating point arithmetic, at a time when machines in this price range used software.[10]
  • to design a PDP-9 controlled parallel computer[11]

Software

The system came with a single-user Keyboard monitor. DECsys, provided an interactive, single user, program development environment for Fortran and assembly language programs.[12]

Both FORTRAN II[2] and FORTRAN IV[13] were implemented for the PDP-9.

MUMPS was originally developed on the PDP-7, and ran on several PDP-9s at the Massachusetts General Hospital.

Sales

The PDP-7, of which 120 were sold,[1]:p.8 was described as "highly successful.".[2] The PDP-9 sold 445 units. Both had submodels, the PDP-7A[NB 1] and the PDP-9/L,[NB 2] neither of which accounted for a substantial percentage of sales.[1][NB 3]

Photos

See also

Notes
  1. sometimes identified by customers and media as PDP-7/A
  2. yes, DEC had a "slash" for the 9/L but not for the 7A
  3. directly mentioned for one, calculated in the other case

References
  1. DIGITAL EQUIPMENT CORPORATION - Nineteen Fifty-Seven To The Present (PDF). Digital Equipment Corporation. 1975.
  2. "RI Computer Museum, DEC PDP-9, System Number 319".
  3. ."The Early Architectures of DEC".
  4. "David Millson - 50 years".
  5. PDP-9 Maintenance Manual, Volume 1 (PDF). April 1972.
  6. PDP-9/L User Handbook (PDF). June 1968. p. 15-8.
  7. C. Gordon Bell; Gerald Butler; Robert Gray; John E. McNamara; Donald Vonada; Ronald Wilson (1978). "Chapter 6: The PDP-1 and Other 18-bit Computers". In C. Gordon Bell; J. Craig Mudge; John E. McNamara (eds.). Computer Engineering: A DEC View of Hardware Systems Design. Digital Press. pp. 154–155. ISBN 0-932376-00-2.
  8. Bob Supnik. "Architectural Evolution in DEC's 18b Computers" (PDF).
  9. "PDP 9 Simulator Configuration". GitHub.com.
  10. Ben Milton Huey (1969). "Design of a floating point processor for the PDP-9 computer". University of Arizona. Cite journal requires |journal= (help)
  11. Wokhlu, Roop Krishen (1969). "The logic design of a PDP-9 controlled parallel computer". Cite journal requires |journal= (help)
  12. Bob Supnik (19 June 2006). "Technical Notes on DECsys" (PDF).
  13. "User Manual - Linkage - PDP-9 Facilities" (PDF). Carnegie-Mellon University Hybrid Computation Laboratory. September 1968. Retrieved 19 September 2017.


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