This is Beagle-Ears
-> Computer History
- 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
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
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.
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)
- 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
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
Replaced CMC -> Beagle-Ears
Revision 1.1 2000/08/15 01:25:08 lars
Rearranged files, moving these from computer/ to comphist/