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PDP-11 Family

Overview
Operating Systems
My Own Experiences with PDP-11
PDP-11 Today

Overview of PDP-11

During the 1970's and 1980's, Digital Equipment Corporation designed and manufactured the immensely successful PDP-11 family of minicomputers.

The PDP-11 family of minicomputers was extremely successful for over 25 years - for good reasons. The instruction set was elegant and flexible, the engineering design was modular in ways that not only allowed the manufacturer to custom build machines of many different price/performance levels, but also allowed users to expand them in the field later. Machines existed in all different sizes; towards the end of its lifespan, the range spanned from personal computers built into a terminal, to time-sharing multiuser systems capable of serving as a common computing resource for an entire university department. This was a family of 16-bit machines with an open hardware architecture (i.e. customers could add new modules from 3rd-party manufacturers, just like with PCs) and a variety of software for different purposes from administrative data processing to real-time process control.

Operating Systems

DEC had several operating systems for these different applications:

RSX-11M for real-time control systems. Generally used by people who programmed in FORTRAN.
RSTS-11 (Resource-Sharing Time-Sharing) for multi-user business applications, and for business programming classes at vocational schools and community colleges. Exclusive programmed in (an extended dialect of) BASIC.
RT-11 for small embedded applications. Only intended for a single user, but there was a 3rd-party add-on called TSX-11 that essentially created a multi-user environment where each user had a virtual RT-11 machine. Programmed in BASIC, FORTRAN, RPG-II and I think there also was a COBOL.
Ultrix-11 - a commercial version of Berkeley Unix

My Own Experiences with PDP-11

The first PDP-11 I saw was an 11/20 running the DOS/Batch-11 operating system at the very new Computer Science department at university of Copenhagen in 1971. Very shortly afterwards, the academic computer center (where I worked) bought a GT-40 vector graphics terminal, which was built around a PDP-11/05. We never did turn it into a useful resource, but it got us introduced to PDP-11 programming using rather simple software development tools. A year or two later, we started building display terminal clusters for the Univac 1100 mainframe out of 11/05 minis, and deployed these all over the university, which was spread out around the city of Copenhagen.

Later, I went to work for a system integration company, where we used PDP-11/35 machines with the RSX-11/M operating system for monitoring 600 MW coal- and oil-burning power plants. We also did some commnucation systems for the two universities.

When I got to California, I worked at a company that had an 11/70 running Berkely Unix.

PDP-11 Today

Though Digital Equipment Corp has gone out of business (absorbed by Compaq), the PDP-11 lives on, and the operating systems are now owned and maintained by Mentec in Ireland.

  $Log: pdp11.htm,v $
  Revision 1.2  2001/10/26 13:28:02  lars
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  Revision 1.1  2000/08/15 01:25:08  lars
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