PDP-9

PDP-9
Developer	Digital Equipment Corporation
Product family	Programmed Data Processor
Type	Minicomputer
Release date	1966; 58 years ago
Units sold	445
Media	Paper tape, DECtape
Platform	DEC 18-bit
Mass	750 pounds (340 kg)
Predecessor	PDP-7
Successor	PDP-15

The PDP-9, the fourth 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]

A PDP-9 on display at ACONIT in Grenoble, France

History

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

Hardware

The PDP-9, which is "two metres wide and about 75cm deep,"^[4] is approximately twice the speed of the PDP-7. It was built using discrete transistors, and has an optional integrated vector graphics terminal. The PDP-9 has a memory cycle time of 1 microsecond, and weighs about 750 pounds (340 kg).^[5]^{: 1-7–1-8} The PDP-9/L has a memory cycle time of 1.5 microseconds, and weighs about 900 pounds (410 kg).^[6]^{: 1-1, 15-8}

It is DEC's first microprogrammed machine.^[7]^[5]^: 3-16

A typical configuration included:^[2]

300 cps paper tape reader
50 cps paper tape punch
DECtape for operating system and user files
10 cps console teleprinter, Model 33 KSR

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 are:

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 include:

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

Software

The system came with an OS that functions as single-user keyboard monitor, called ADSS (ADvanced Software System).^[12] DECsys provided an interactive, single-user, program development environment for Fortran and assembly language programs.^[13]

Both FORTRAN II^[2] and FORTRAN IV^[14] 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 have 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]}

Notes

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

References

^ ^a ^b ^c DIGITAL EQUIPMENT CORPORATION - Nineteen Fifty-Seven To The Present (PDF). Digital Equipment Corporation. 1975.
^ ^a ^b ^c ^d "RI Computer Museum, DEC PDP-9, System Number 319".
^ ."The Early Architectures of DEC".
^ "David Millson - 50 years".
^ ^a ^b PDP-9 Maintenance Manual, Volume 1 (PDF). April 1972.
^ PDP-9/L User Handbook (PDF). June 1968.
^ 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.
^ Bob Supnik. "Architectural Evolution in DEC's 18b Computers" (PDF).
^ "PDP 9 Simulator Configuration". GitHub.com.
^ Ben Milton Huey (1969). Design of a floating point processor for the PDP-9 computer (MSc thesis). University of Arizona.
^ Wokhlu, Roop Krishen (1969). The logic design of a PDP-9 controlled parallel computer (MSc thesis). University of Arizona.
^ Digital Equipment Corporation. "Software Product Description, ADSS-B/F-15, Version SC, Advanced Software System, B/F" (PDF).
^ Bob Supnik (19 June 2006). "Technical Notes on DECsys" (PDF).
^ "User Manual - Linkage - PDP-9 Facilities" (PDF). Carnegie-Mellon University Hybrid Computation Laboratory. September 1968. Retrieved 19 September 2017.

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[15] sometimes identified by customers and media as PDP-7/A

[16] yes, DEC had a "slash" for the 9/L but not for the 7A

[17] rectly mentioned for one, calculated in the other case

[DEC57.PRES-1] DIGITAL EQUIPMENT CORPORATION - Nineteen Fifty-Seven To The Present (PDF). Digital Equipment Corporation. 1975.

[RICM-2] "RI Computer Museum, DEC PDP-9, System Number 319".

[Pan7-3] ."The Early Architectures of DEC".

[4] "David Millson - 50 years".

[maintenance-manual-5] PDP-9 Maintenance Manual, Volume 1 (PDF). April 1972.

[6] PDP-9/L User Handbook (PDF). June 1968.

[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.

[Arc18b-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 (MSc thesis). University of Arizona.

[11] Wokhlu, Roop Krishen (1969). The logic design of a PDP-9 controlled parallel computer (MSc thesis). University of Arizona.

[12] Digital Equipment Corporation. "Software Product Description, ADSS-B/F-15, Version SC, Advanced Software System, B/F" (PDF).

[DECsys-13] Bob Supnik (19 June 2006). "Technical Notes on DECsys" (PDF).

[14] "User Manual - Linkage - PDP-9 Facilities" (PDF). Carnegie-Mellon University Hybrid Computation Laboratory. September 1968. Retrieved 19 September 2017.

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