Home Up

Later this year, on 11th June 2050 to be precise, the RSTS/E Operating System will be eighty years old.

This presentation will review how it has changed over the years, from the original Version 2A of the early 1970s, right up to the latest release (29.6) this year. Particular emphasis will be placed on its revival period from 1989 through to 1999 which saw it re-emerge as Digital's Number 1 Operating System following announcement of the “New Range P90” VAX/VMS system replacement.

The changes in PDP-11 hardware, from the chips and boards approach of the 1980s through to the VVVLSI (Very, Very, Very Large Scale Integration) of today will also be discussed.

The Speaker, a Certified Mature Programmer, is the Founder of the U.K. RSTS/E Preservation Society.

The Story of RSTS starts over 100 years ago ...



Project Whirlwind was the first electronic computer able to operate in real time and was programmed as a flight simulator.

The system was used between 1945-1959, occupied 3,100 square feet, had over 5,000 valves (plus 11,000 diodes) and required 150K watts to run. Only one system was ever built-at a cost of about $5 million (ie over 200 billion in todays money).

There are two connections between Whirlwind and the PDP-11.

Not only did a young Ken Olsen work on this project, but the Whirlwind computer was based on a 16-bit architecture.



Ken Olsen stayed with MIT until 1957 when he left and formed Digital Equipment Corporation. Folklore tells us that Ken Olsen started the company using his garage to assemble circuit boards.

The reality is even more extraordinary.

The company did start with just three other people, one of whom was his brother Stan Olsen, who took the role of Sales Manager. (The original business plan shows a final requirement for a total of 10 employees.)

It also started with 8500 square feet of production space on the 3rd floor in the “converted” woollen Mill Building Twelve and with a $70,000 loan from American Research and development venture capital company. Ken Olsen says “The nice thing about seventy thousand dollars is that there are so few of them that you can watch every one”.

The company's first products, logic modules, were dipped in fish tanks containing solder.

Digital Equipment Corporation officially started to trade on August 23rd.



PDP-1 announced. It cost only $120,000. The word PDP was used to avoid the word “computer”, since a central buying policy by the US Government meant it was much more difficult to sell a “computer” than a “Programmable Data Processor”.

Although the PDP-1 was both designed and sold in 1960, no deliveries were made until 1961.



A boost for computing came when President Kennedy decided that not only would America land a man on the moon before the end of the decade, but that it would also bring him back safely.

March-DECUS formed and used the outline of the PDP-1 console as its trademark.

The first PDP-11 is delivered to Bolt, Beranek and Newman-among the early users are Lucy Darley, Tom Evans, and Tim Hart.



PDP-4 announced.



PDP-6 announced-the first commercial computer designed and used for timesharing.

September-Porsche announce 911 at Frankfurt Motor Show.



BASIC was invented by John G Kemeny and Thomas E Kurtz at Dartmouth College, New Hampshire. BASIC stands for Beginners All-purpose Symbolic Instruction Code.

Digital opened first UK office above Bilbury's furniture shop in the Butts, Reading.



PDP-8 and LINC-8 (Laboratory INstrument Computer) introduced.

Southampton University (UK) buy a PDP-8. Roger Deakin joins Digital in the UK.



The first European DECUS Seminar is held in London-there are 51 attendees.



TSS/8 operating system (Time Sharing System for PDP-8) released.



Bruce Delagi working on PDP-11 design, on the second floor of Mill Building five. Jim O'Loughlin working on CPU Logic design.

(Ken Thompson and Dennis Ritchie start work on UNIX using a PDP-7 based system.)

Summer-first internal attempt to put timesharing on a PDP-11 was started. MUM-11 (Multi-User Monitor) was added on top of DOS-11 and included a variation of single-user BASIC-11 which ran very slowly.

Consolidated Computer market Key-Edit system based on PDP-8 processor supporting up to 32 key-to-disk terminals.



5th Feb-Andy Knowles and Julius Marcus, product line managers, announce the PDP-11/20, based on KA11 processor. Over 150 orders were taken in first week.

Feb-Eric Coates joins Digital UK as the first PDP-11 Software Support Engineer. He is also involved with “tolerance testing” the final prototype-blowing cigar smoke through the cooling fans.

The first operating system was PTS (Paper Tape System) and included PAL-11, ED11, ODT-11, IOX, Math Package Loaders and core dump routines.

The second operating system was DOS (Disk Operating System), which included a PAL-11 compiler. (PAL-11 was renamed as MACRO a few years later.)

This was not a “funded” project-it was simply written by engineers who got bored with waiting for PTS to be loaded.

April-Radiation Inc and Computer Machine Corporation received first two systems.

Initial configuration included:-

PDP-11/20 with 32K words core memory, RF11 256K words fixed-head disk, TU56 dual DecTape drive, KW11 Real-time clock, M792 Bootstrap Loader, Console teletype, DOS and FORTRAN IV compiler.

*** RSTS was born on 11th June 1970. ***

Of course it was not called RSTS then-but simply IOX, standing for Input Output eXecutive, which had been developed as part of PTS.

The decision to write a multi-user operating system had been taken several months earlier and Tom Barnett assigned as Product Manager. Nathan Teicholtz (an ex-TSS/8 software engineer) leads the design team.

However delays had been caused by internal feuding as to which language should be supported. The battle lines were drawn up behind two camps.

The choice was between FOCAL (FOrmula CALculator) and BASIC.

It was left to the marketing people to decide, since on a technical level these two languages were considered the same.

(Nobody thought that the limited character handling of FOCAL would represent any significant problems.)

The FOCAL supporters had two main arguments: the language already existed on the PDP-8s and (more importantly) it conformed to the fundamental Digital philosophy-“Let's be different”.

The more the BASIC camp argued in favour of needing an industry standard, the more the FOCAL people repeated-“Let's be unique”.

In the end a classic compromise-a unique BASIC.

Needless to say, the sales people liked this since HP were considered a threat with their BASIC. So the Digital product became BASIC PLUS.

Now there was a new problem. In summer 1970 the Digital development team were working on the IOX monitor-so nobody was available to write BASIC PLUS.

Enter the cavalry-a small specialised software house called Evans Griffith and Hart that had already established itself as a “star” with the worlds first LISP compiler. (The founders, like Ken Olsen, had also been at MIT.)

Computerworld article, dated 05-Aug-70, describes an “IL” compiler written by Tom Evans.

Dave Knight suggests that EG&H should contact Hank Spencer as it seemed likely that Digital would contract out a project to “implement the BASIC Editor/Compiler for a PDP-11 Multi-user BASIC”.

On 25-Aug-70 Digital sent out a two page invitation.

The reply, dated 04-Sep-70, from EG&H was even shorter-just over one page. Yes, it could be done within three elapsed months-and for a fixed price of $10,500.

(To put things into perspective, this was less than the sale price of a basic PDP-11/20!)

Digital accepted the EG&H quote on 18-Sep-70 and even offered a $3,000 bonus if the deadlines were met-Tom Evans was designated project manager.

Sadly, EG&H did not receive a “per sale” royalty payment.

The original idea had been for EG&H to write the BASIC PLUS lexical analyser and create the “push pop” code. A Digital employee would have handled the actual execution of a program, ie what happened after you typed RUN.

(The logic behind this idea was that RSTS would also have been available as a “run only” system with no compiler, thereby greatly increasing the maximum program size, depending on how much of the compiler could have been deleted.)

In reality, EG&H were left to do everything-and Tim Hart (the H bit of EG&H) wrote the majority of the code and finished it during January 1971. The run only system was abandoned.

It was during this period that the IOX project became BTSS-Basic Time Sharing System.

This was only short lived-since Honeywell already had a product with the same name.

So BTSS became RTSS-Resource Time Sharing System, which in turn (through the simple mistyping) became RSTS-Resource Sharing Time sharing System. RSTS 11 Version 1 was never released.

The first RSTS system was to have been made available for viewing at the Fall Joint Computer Conference but changes in design considerations prevented this debut.



Mark Bramhall joins development team on a temporary basis in order to “get the first release out”. The system size grows-and now exceeds the target 16K word limit.

RSTS Version 2A-19 delivered to Carleton College, with the monitor on paper tape. There were no utilities. Mark Bramhall writes a primitive SYSTAT so that one could see what was going on with the system.

Seattle Pacific College is donated a system-Ken Olsen had been a student there.

Although a 16 user system, the computer manager only allowed one user to run at a time. He had thought it quite amazing that multiple keyboards could access the system-but, being an ex IBM 1401 man, it never occurred to him that they could do it at the same time.

June-RSTS Version 2B. The third system went to The Delaware School Auxiliary Association.

Each of the 18 schools were equipped with a 110 baud modem and while the first 16 were logged in, the remaining two continued to dial in waiting for a free job slot.

Auto restart code was added by a young software services manager called Ted Sarbin.

The 11/45 was announced-and with it a choice of memory, Core, MOS or Bipolar, at a basic cost of $20,000.

A typical 11/45 configuration included basic CPU with 32K words, MM11-LP (8K parity core memory), RF11-A (262K swapping disk unit), RK11-D (1.2 million word DECpack disk unit), TC-11-G (DECtape unit) and QR430-AC (Timesharing system software Licence plus 6 training credits). Cost: £46,200 in the U.K.

October-RSTS Version 2C. Record I/O was added for a company called Reynolds & Reynolds. (It had, until this moment, always been assumed that a combination of sequential ASCII files, plus Virtual Arrays would be sufficient for all disk handling.)

Early (pioneer?) commercial users include Modern Talking Picture Service, Prudential, Continental Can and Missouri Pacific Railroad.

November-Nick Brackenbury joins Digital in U.K.



January-RSTS Version 3A-19.

This ran on an unmapped 11/20 machine, ie the 28K words was all the memory that was available for the entire operating system, BASIC language and space for up to 16 online users.

Note that the 8K word Swap Max was reduced to 4K words if you only had 24K words system.

You did not receive a “Ready” prompt after logging in, but instead the message “NEW OR OLD”.

This may have referred back to the original idea of having a development SIL and a “run only” SIL, where the prompt for the “run only” SIL might have been “RUN WHAT”.

It is thought that the first UK non Digital employee to use RSTS was David Peel, who at that stage was working for The British Steel Corporation.

He logged on to a system called “EUROPE” in Reading at 02:54 PM on 9th January 1972. His first program was the immediate mode command “PRINT 12^2”. The system displayed “144”.

At the end of a three hour session, David had written a slightly larger program to generate lots of Pythagorean triples. For his managerial peace of mind he checked that the program could be saved to DECtape and restored from a different handler at a different terminal into a different account.

Apparently while the Digital “minder” thought he was mad, she had never worked on other computer systems where nothing was taken for granted.

David came away impressed-and British Steel placed an order.

May-RSTS Version 3B. There are no known users.

June-RSTS Version 3C. At long last we have the first recorded “wish list” item about RSTS from Bob Branton, at Southeastern State College.

Under Version 3C, the monitor was unable to write to a disk file from a terminal while reading that file from another terminal. His “wish” was granted with creation of UPDATE mode.

Both Nathan Teicholtz, who added the RSTS monitor code to support UPDATE mode, and Tim Hart, who changed Basic Plus to include MODE 1, finished their respective sections in less than one day.

New devices included RK03 disks. Basic Plus now supports both 2 and 4 word maths package. (3 word package dropped).

Among the first UK RSTS users were Wylies, Hurst and Sandler, Airfix, Cable Belt, British Aerospace and Green Shield Stamps.

The PDP-11/40 was announced as being “1.8 to 2 times faster than PDP-11/20” and had a memory management unit which extended the maximum usable address space from 28K words to 124K words.

An internal Digital debate took place on the feature that became known as SEND/RECEIVE as to whether a “message” should be sent, or whether the calling job should simply change the contents of the receiving jobs memory. The message idea “won” as it catered for a swapped out job to receive a message.

The description “LOAD CORE COMMON” referred to those early days when CORE memory was used.

October-RSTS Version 4A. Support was increased to include the newly announced 11/40 and 11/45. SYSGEN was under DOS. (Prior to this, all Sysgens had been done by Digital and no SYSGEN kit was available.) All CUSPS, written in Basic Plus, were built from paper tape sources at 10 cps using ASR33 teletypes.

Martin Minow joins Digital in RSTS support.

Both VT05 (20 lines by 72 columns) and RT02 (1 line by 20 columns) were supported as additional SCOPE devices. NB The VT05 required a FILL 4 if used at 1200 baud.

The complete documentation set amounted to 3 manuals:- Basic Plus Language, RSTS users and the System Managers Guide. Total cost $22.50 - excluding binders. The ROLLIN backup manual was not part of the documentation set and was supplied free of charge.

RECORD I/O was optional and there was a separate SYSGEN sub option for UPDATE mode which required an extra 75 words.

There was a reference to a BADS file that might be used in future releases.

Hardware supported included both fixed disks (ie 512K byte RF11s) and removable disks (2.4 megabyte RK05s).

The garbage collector was not FIP overlaid and it swapped out the program and had to read it back in again. The command CAT almost stopped the system.

PI was not write protected: i.e., if you were tired of it being 3.142 you could make it 3.1 or 3.2 as you wished.

Maximum program size was 8K words but this could be PATCHed to 10K if you were an “expert”. The Job Max remained at 16 Jobs.

The system startup message was slightly strange and included the phrase “Catastrophic Error-Program Lost-Sorry”.

The program SHUTUP achieved the system closing down by PEEKing at an odd address which caused the machine to crash.

ROLLIN used as a stand-alone program to copy data between two disks, or disk and magnetic tape.

The operating system file extension was changed from .CIL (Core Image Library) to .SIL (Saved Image Library).

December-School District No 91 at Idaho Falls took delivery of its RSTS Version 4A 48K byte PDP-11/20 system, complete with two RK05s, two DECtapes, card reader and 60 lpm line printer. A DECUS Fall 1973 Paper by John Christensen notes that when all 6 terminals are in use simultaneously “the response time becomes poor at times”.

On December 29th, David Allen ordered a PDP 11/40 with two RK05s and a DC11E (two line interface with both modem control and programmable speeds)-and Allen Computer International became the first PDP-11 bureau in the U.K.



January-James O'Loughlin (PDP-11/40 Project Engineer) describes the differences between PDP-11/20 and PDP-11/40 as being “specific and obvious product improvements”.

March-RSTS training course given by Harold Houland in the UK was not going to cover Record I/O-since he didn't know about it. A software support specialist from Manchester called John Gow came to the rescue.

Bob Branton starts the RSTS SIG in the States serving as its chairman.

Ross Miller writes new backup package (BACKUP and BACKDK) over July 4th Weekend.

July-Paul Koning encounters Version 4A system running on a PDP-11/20 at Lawrence University.

RSTS/E Version 5A/21. It no longer supported the 11/20. SYSGEN was under DOS but at least you had batch command files to save all the manual typing.

Hooks were in the operating system for multiple Run Time Systems- but were not yet used.

The TECO Run Time System was emulated by two Basic Plus programs.

Swap Max was still 8K words for normal users but 16K for privileged users. Job Max was doubled to 32 Jobs. The maximum machine size was 128K words, of which 124K was usable.

A total of over 25,000 PDP-11s had been shipped.

The first UK Memory Management unit was installed by Digital engineer Alex Taylor on the Green Shield Stamps PDP-11/40 at Daventry. Eoin Hanley (CAP) performed the SYSGEN upgrade from RSTS-11 Version 4A to Version RSTS/E 5A. (This joint operation took two and a half days.)

October-Fred Knight begins a four year course learning as many ways as possible to break into RSTS.

“101 Basic Computer Games”, edited by David Ahl, available for $5.00 from Software Distribution Centre included several contributions from Rusty Whitney and SPACWR from Mike Mayfield.

John Gow leaves Digital UK to start officially Systime.



January-J.M.Hill and Sons take delivery of PDP-11/40, 32K words, 4*RK05 disk drives and 300 LPM printer. This RSTS-11 V4A site was upgraded to RSTS/E V5A (and 48K words) when poor response times were encountered with only eight online users.

February-Clark Baker, George Robbins, Dan Grim and Ed Baker write the PPCODE Basic Plus Decompiler.

November-RSTS/E Version 5B/24. It allowed for CCLs as long as you created them during SYSGEN time. EDIT and EDITCH were introduced. Auto answer was introduced for SYSGEN generations and so were multiple SWAP files.

There was a hidden option for overlapped seek with multiple disks. Among the new BASIC PLUS commands were CVT$$, STRING$, STATUS, BUFSIZ.

Commercial Extensions were available which included Sort (XQWIK, SQWIK, MQWIK, OQWIK) IAM functions, QUE, SPOOL and a Decimal Arithmetic package.

Hardware included the RP03, (40M byte disk drive), DH11s and 1200 LPM printers. APPEND as a command was introduced.

It was an extremely untidy release.

Multiple Run Time Systems being added by Steve Gray working for British Steel to get a FORTRAN Compiler to run under RSTS.

Systime increase the Version 4A maximum program size to 16K words on PDP-11/04 based systems.



February-the first microcomputer (LSI-11) introduced, March-RSTS/E Version 5C-01. This in fact was a PATCHed version of Version 5B and contained no new commands.

Internal Digital Inter-office memo from Ted Sarbin in Software Services dated 03-Jun-75 describes the Oregon Museum of Science and Industry OMSI-RT Run Time System. He observes that an OMSI FORTRAN version of a Basic Plus program runs five times faster.

July-first PDP-11/70 installed in USA.

(The first 11/70 made in Galway, serial number 040-5000, was sold to Allen Computers.)

RSTS version 4B was released during the summer of 1975. It contained no new code and was simply a fully PATCHed version of 4A and marked the end of RSTS 11.

August-Dr John Jones denies that Slot 19 in the 11/70 CPU has been left empty for any particular reason.

RSTS/E Version 6A-02. Support was now for the 11/35, 11/40, 11/45, 11/60 and 11/70. The Job Max had been increased to 63 jobs and maximum memory on the 11/70 was now 2M bytes. The RP02 and the RP04 were added.

Multiple Run Time Systems were available: i.e., COBOL, FORTRAN, SORT11 were all added. XBUF was introduced. Pseudo keyboards introduced as well. STATS was a hidden option. The VT50 was the replacement for the original VT05 and TU16s were available.

PRESRV available as a stand-alone program to copy data from disk to disk, disk to tape, tape to tape and (to restore data to its original device) tape to disk.

IAS (Interactive Application System, developed at Reading, UK) is announced.

Page 106 of the RSTS Version 6A terminal service source code contains the comment:  “This conditional is dedicated to DEC engineering without whose help it would have been unnecessary”.

October-Alan Browne starts DECUS UK PDP-11 Commercial Users SIG.

November-MBI Data Processing announce Version 1 of MISAM, Multiple Index Sequential Access Method.



PDP-11/34, RMS-11 and DBMS-11 announced.

January-Simon Szeto joins development team, having previously been a Version 4A customer in 1973.

March-Eoin Hanley and Eric Bell set up Systems Optimisation.

Anton Chernoff appointed RSTS Project Leader, having previously got involved in almost all aspects of development. In particular he had revamped INIT.SYS to include auto-configure logic, removed the dependancy on DOS for SYSGENs, implemented the first RT-11 Run Time System and wrote the much needed auto-patch feature.

September-RSTS-11 SIG Newsletter has Bob Branton as editor and chairing the sub groups were Stu Katz, Roy Swatzell, Howard Kipple, Bill Tabor, Ardoth Wilson, Bill Sconce and Murry Stinson.



January-1000th PDP-11/70 delivered.

February-RSTS/E Version 6B-02. SYSGEN was now under RT11. New hardware included RK05Fs, RK06, RP05, RP06, DZ11, LA180. Contiguous files were allowed. CCLs could be added at run time. EXTEND mode was introduced. Echo control mode 8. Among the Run Time Systems allowed were BASIC PLUS 2, FORTRAN, COBOL, RPG2, APL, RMS-11, RT11 and a new BACKUP package.

March-Accessories and Supplies Group (A&SG) make 3-inch blue vinyl binders available to catalogue all the published patches.

Computerworld reported that “OMSI Sort-1 whips DEC utility used under RSTS/E”. The software ran under the OMSI-RT emulator and was available for both Versions 6A and 6B.

New PDP-11/700 system introduced (VAX). First model, 780, has two RK07s and 128K bytes of memory. It does not run RSTS.

CTS-500 announced as a software package that included RSTS/E Version 6B, Basic-Plus, Dibol-11 and DecForm.

PDP-11/60 (first system with loadable microcode) announced.

October-Internal Specification for RSTS/E version 6C issued by Simon Szeto, approved by Bob Daley, Dian Pekin and John Morgan. Development team included Mark Bramhall, Anton Chernoff, J Miller and J Wooldridge.

January-1000th PDP-11/70 delivered.

February-RSTS/E Version 6B-02. SYSGEN was now under RT11. New hardware included RK05Fs, RK06, RP05, RP06, DZ11, LA180. Contiguous files were allowed. CCLs could be added at run time. EXTEND mode was introduced. Echo control mode 8. Among the Run Time Systems allowed were BASIC PLUS 2, FORTRAN, COBOL, RPG2, APL, RMS-11, RT11 and a new BACKUP package.

March-Accessories and Supplies Group (A&SG) make 3-inch blue vinyl binders available to catalogue all the published patches.

Computerworld reported that “OMSI Sort-1 whips DEC utility used under RSTS/E”. The software ran under the OMSI-RT emulator and was available for both Versions 6A and 6B.

New PDP-11/700 system introduced (VAX). First model, 780, has two RK07s and 128K bytes of memory. It does not run RSTS.

CTS-500 announced as a software package that included RSTS/E Version 6B, Basic-Plus, Dibol-11 and DecForm.

PDP-11/60 (first system with loadable microcode) announced.

October-Internal Specification for RSTS/E version 6C issued by Simon Szeto, approved by Bob Daley, Dian Pekin and John Morgan. Development team included Mark Bramhall, Anton Chernoff, J Miller and J Wooldridge.

November-First version of REPGEN (REPort GENerator) goes live as part of Digital internal OAS project. A single PDP-11/45 with three RP03s is all that is required to handle the whole of the UK's Sales Order Administration System.



February-RSTS/E Version 6C-03. TECO and VTEDIT were released as part of a DECUS supported package. DECnet, DATATRIEVE-11 and DIBOL/DECFORM are now available.

Auto patch facility added to “reduce long, tedious process of applying patches during system installation”.

PIP.SAV replaced the old PIP and PIP EXTEND. Also the program STATUS, from Martin Minow, which has never been fully “supported” by Digital. Hidden options included the words GET BLOCK and SPEC% and a fancy null job that shows a left shifting pattern in the “data” lights and a right shifting pattern in the “memory address” lights-RSTS/E becomes the first Digital operating system to support SUPERVISOR mode.

March-An internal Digital Report on Hardware and Software Selection Strategy for Manufacturing Information Systems refers to RSTS/E as “Product verging on senility due to monitor size (no core left for growth)”.

May-TRAX announced. In the UK there were four users-only three of whom were unhappy.

June-SAVRES Specification (58 pages) signed off by Nancy Covitz as project leader.

August-Ted Webber (Planning Manager) hosted RSTS/E Version 7.0 System Review that showed the project was within $6.5K (underspent!) of $333.1K budget for FY78, with an additional budget of $412.9K for FY79.

August-“RSTS/E System Programmers Notebook” published by Martin Minow starts by saying it should have been entitled “Everything you always wanted to know about RSTS/E performance but were afraid to ask”.

The “Computer Engineering” book, a DEC view of hardware systems design, states that “a major side benefit of TSS/8 was the training of the implementors, who went on to implement the RSTS timesharing system for the PDP-11 based on the BASIC language”.

August-RSTS/E Version 7A Functionality Goals and New Features Document states that “The following hardware will be supported if resources and schedules permit:-

TS04 magtape system, RP07 disk, PDP-11/44 processor including PAX, Fonz (PDP-11/24) processor, RL02 disk subsystem, use of the commercial instruction set within the RSTS/E monitor for FORTRAN IV-plus”.

August 9th-RSTS/E Version 7 System Review meeting involved Ted Webber, Bob Daley, Doug Maclean, Mike Marcil and Ed Spuler.

August 17th-Small Buffer article entitled RSTS/E V7A CANCELLED. “We are saddened to report that the Corporation has decided that there will be no RSTS/E V7A... it was finally decided that the need for compatibility among all Digital software products requires the demise of V7A”.

August 31st-Small Buffer article entitled RSTS/E V7.0 IS VERY MUCH ALIVE. “...This was meant to be a humorous commentary on corporate standards. Absolutely nothing has changed on the RSTS/E V7A project except that the official name of the release which is now RSTS/E V7.0”.

September-Presentation made by Martin Minow at DECUS Copenhagen starts with the words:- “There is definitely a future for RSTS despite TRAX, VMS etc. It is the only general purpose timesharing system available on the PDP-11”.

October-Hamish Donaldson writes a book entitled “A Guide To The Successful Management Of Computer Projects” based on his experience of RSTS systems at Hill Samuel.

October-Nick de Smith returns to Dulwich College, where he had been a student between 1967 and 1976, to write the DECOMP Basic Plus Decompiler.



April-Walt Klefer states, in the System Evaluation Plan, that the PDP-11/44 computer is based on the PDP-11/34A design with essentially the functionality of the PDP-11/70.

July-Internal Small Buffer article by Gary Alles describes the DUMP and DEBUG features (including TRACE and BREAK commands) that will be available in RSTS Version 7 as “unsupported optional features”.

September-Julius Marcus, VP Commercial Systems Group, says that newly announced Datasystem 540 established “a new standard” for midrange systems.

November-Internal Small Buffer article by Win Hindle and Julius Marcus states “RSTS/E systems are mainstream products whose sales volume is expected to significantly increase over the next few years”.

December-RSTS/E Version 7.0. Supported CPUs now included the 11/24, 11/34, 11/35, 11/40, 11/44, 11/45, 11/60, 11/70. RDC was introduced.

SYSGEN was now under RSTS during time sharing and data caching was introduced. The RSX monitor allowed 31K word programs. Maximum memory on an 11/70 was now 4M bytes, of which 3840K bytes were addressable.

Resident libraries were introduced. XBUF for line printers. SAVRES for backup. A new version of FIP called large file FIP was created and by now they had of course stolen the switch panel for RDC so that sexy lights were no longer possible.

November-first edition of RSTS PROFESSIONAL (edited by Carl Marbach and Dave Mallery) included articles on Structured Programming (Al Cini), In-house Timesharing Systems (Ken Ross), RSTS Directories (Scott Banks) and MACRO-11 (Richard Marino).



RSTS SIG at DECUS Chicago-Tom Harris, Jeff Killeen, Mark Bramhall, Stu Katz, Errol Ethier, Glenn Dollar, Nancy Covitz, Charles Mustain, Bill Tabor and Bob McCormick.

N. Long at Digital Epsom (UK) produces a document called “Migration from RSTS/E to VAX/VMS By Translation not Emulation”. It is 75 pages long.

April-VAX-11 Basic V1.0 announced as a “superset of PDP-11 Basic-11, Basic-Plus and Basic-Plus-2 and is designed to ease the transition for users moving programs written in Basic from the PDP-11 to the VAX-11”.

July edition of RSTS/E Software Dispatch was 270 pages-28 of which detailed the differences between V7.0 and V06C.

The newly added support for subroutines written in MACRO-11 meant that 4 new manuals were added to the documentation set: System Directives, Programmers Utilities, FORTRAN IV Utilities and IAS/RSX ODT Reference Manual.

Software distribution available on: 7-track 800 bpi, 9-track 800 bpi, 9-track 1600 bpi magnetic tapes, RK05, RK06, RK07, RL01 and RL02 disk cartridges.



PDP-11/23 plus announced.

January-Evans Griffith & Hart announce Version V02.00 of ROSS/V-the technical summary is 23 pages.

February-Commercial Marketing produce first copy of RSTS/E-VMS COEXISTENCE AND MIGRATION Manual. It contains 72 pages, including a section on converting IBM COBOL to VAX-11 COBOL.

Paul Laba, Computer Services Manager at Le Moyne College, documents a bug in FIP in a RSTS Professional article and comments: “..DEC further noted that the problem is difficult to repair and would not be corrected until the next RSTS release (will there ever be a next release?)”.

April-RP07 (516 megabytes) and TU78 (1600/6250 bpi at 125 ips) announced for DECsystem 10 and Vax. No announcement for RSTS/E.

Frank da Cruz and Bill Catchings of Columbia University for Computing Activities at New York implement first version of KERMIT between DECSYSTEM-20 and CP/M-80 microcomputer.

September-VT101, VT102 and VT131 introduced.

November-DECUS Fall presentations include The Soggy Marshmallow Theory in relation to solving the RSTS Small Buffer Problem.



January-Paul Laba, against all odds, joins the RSTS group as a software engineer.

February-RSTS/E Version 7.1. This now uses separate I&D space to relieve the small buffer problem. DECnet/E Phase III V2.0 route through is allowed. DCL (in a very primitive form) is introduced. Kernel mode I&D space support.

May-TSV05 magnetic tape subsystem for 11/23 and 11/23 Plus.

Rainbow, DECmate and Professional micro computers announced. (Although the Professional was based on the PDP-11 it did not run RSTS).

June-Micro-11 Systems introduced.

June-“The industry's highest-capacity rack-mountable disk storage units with fixed and removable media have been announced by Digital Equipment Co. Ltd.” stated the press release about the RA81 and RA60 disk drives.

June-DECUS UK PDP-11 Commercial Users SIG present “The Professionals Are Back” seminar with Al Cini, Dave Mallery and Carl Marbach.

Fred Knight joins RSTS Engineering.

August-RSTS/E Version 7.2. Supports new UDA50 disks: i.e., the RA80. The typical machine is now an 11/44, 1M byte of memory, RA80, TS11, DZ11E for under 50,000 pounds including a general licence.

September-first edition of DEC USER (incorporating Network) includes article on “Downgrading to VAX”.

November-First edition of RSTS/E Monitor Internals written by Mike Mayfield.



April-RSTS/E Version 8.0-06. Support for the recently announced PDP Micro 11/23 system (RD51 10 megabyte disk, 2*RX50 400K byte floppies, 128K words memory).

Many TS11 (45 ips) users tried to upgrade to newly announced TU80 (100 ips), only to discover that the TU80 would only run at 25 ips in start/stop mode.

TK25 tape drive available on Q-Bus systems.

BASIC Version 2 now allows 31K words and “no overheads” for the use of RMS.

New disk structure caters for GFD between MFD and UFD.

New spooler, part of micro RSTS packaging, supplied with standard (ie old) spooler.

September-Tim Leisman, SW Product services, confesses in an internal memo that 42 “software defects” have been identified in Version 8.0-Update B solves 90% of the problems.

Black Tuesday (October 18th)-Digital Stock fell 21 points.



February-An Addendum to The History of RSTS published in RSTS Professional observes that “...The Men in Marketing may have decided that RSTS is already too popular”.

Summer-Quantic Computing (co-founded by David Peel and John Robinson) announced BAS24K, a software product that increases the maximum program size of Basic Plus programs to 24K words.

Patch kit F incorporated a new release number (8.0-07) and included a new INIT.SYS to support 11/84 CPUs.

All 11/84s have to have co-processor chips removed.



May-RSTS/E Version 9.0-14 included more changes than any release in the history of RSTS.

New supported hardware included TK50, QDA50 and RC25. TU80 now “streams” under BACKUP.

New BACKUP program, DCL greatly enhanced, multiple levels of privilege, PBS (Print Batch Services), indirect command files, long hashed passwords.

BP2, FORTRAN 77 and Macro have increased maximum program size to 64K words.

RSTS 15th Birthday Party held in New Orleans included Jeff Killeen as BOZO and first presentation at a DECUS USA Symposium by The RSTS UK SIG Founder.

June-CLUSTER-11 hopes to allow users to configure their systems with an additional five to 15 tightly coupled J11 processors running RSTS/E programs.

Paul Laba appointed RSTS Development Manager.

October-RSTS/E Version 9.1-05 doubled the maximum number of MSCP disk drives to 16, introduced multi-threaded FIP and support for new high end Q-Bus systems based on 11/83, RQDX3 and RD53 with TK50 becoming a new distribution device.

Changes to DU disk driver, LOAD INDEX feature and FIP cause negative system performance gains.

The full list of PDP-11 operating systems then available:-

RT-11, RSX-11S, RSX-11M, RSX-11M+, Micro/RSX, RSTS/E, Micro/RSTS, DSM-11 (Mumps), ULTRIX-11, IAS, CTS-300, MicroPower/Pascal.



April-DECUSER publish article entitled “Today's VAX users return to RSTS”. The article, dated April 1st, states that “The main reason for migration is that we all now know that while development of RSTS and PDP-11s continues, VMS has been declared a “mature” product”.

May-Systime sold its Digital related hardware activity to a group of employees lead by Roger Deakin in a management buyout to form Instate Technology Ltd.

Jeanne Davis assumes Product Management responsibility for RSTS/E, DECNET/E and other layered products.

June-RSTS/E Version 9.2-10 supported the new low end Q-Bus systems based on 11/53, RQDX3 and RD31 with RX33 for backup device. In addition, the TU81 plus TMSCP support now available as an MU device.

DECUS Newsletter shows SIG leaders include Charles Mustain, Scott Pandorf, Wef Fleischman, Bruce Gaardner, Philip Hunt, Errol Ethier with Joel Arker as DEC Counterpart.



January-RSTS/E Version 9.3-20 is announced with support for 11/53, new semi-sexy lights null job on 11/84 systems, general improved performance and support for DECnet/E Version 4.

New SELECT qualifier allows file selection based on file size.

Software Product Description shows full range of supported processors:-

PDP 11/23, 11/23 Plus, 11/24, 11/34, 11/35, 11/40, 11/44, 11/45, 11/50, 11/53, 11/55, 11/60, 11/70, 11/73, 11/83 and 11/84.

June-Ken Olsen goes on record saying “We will be in the PDP-11 business a very long time”.

(Editors note: At the time few realised that “a very long time” meant that PDP-11s would be around in the year 2050!)

July-RSTS/E Version 9.4 incorporated a 5% improvement to the scheduler, faster PIP directories (using OPENXT monitor call) and documentation on how to program the Ethernet DEUNA, DELUA, DEQNA hardware interfaces.

PDP-11/84 co-processor chips now working.

Terminal service performance improved.

DECnet Ethernet supported via “reverse LAT” hardware.

Support for newly announced 11/53 Plus, RD32 (42 megabyte disk) and DHQ11 (dual height 8 line interface).

PDP 11/83 reclassified as L Class systems for Licences.

Micro Systems Development head count reveals:-

RSX                         36

Languages             34

RSTS                        28

RT                           24

DSM                         8

August-The LINK (developed by Mike Mayfield at N.D.S.) allows the clustering of two PDP-11s so that overall system performance is greatly increased.

December-The RSTS/E and VMS Compatibility Guide by Ken Hobday and Mark Buda runs to 98 pages.

December-RSTS/E Version 9.5-08 catered for the RA82 disks by increasing the pack clustersize to 64 and allowed jobs stuck in FP(MTA) state to be killed.

A new TKB fast mapping directive was released.

At long last BACKUP was enhanced with a /DIRECTORY command to discover what was on a tape.

Selective zeroing of errors by error type now supported.

Converting Basic Plus/Basic Plus 2 to Vax Basic guide published- only 100 pages.



April-The LINK on display in Digital exhibition area at the DECUS UK Conference.

May-Dom LaCava, manager of Micro Systems Development, introduces over 50 members of his team at the “DECUS meets MSD” session held at Cincinnati.

Fred Knight makes a “program announcement” that Version 9.6 will have support for LAT Ethernet terminal servers.

WPS-Plus now available under RSTS/E. RX33 floppies can now be formatted.

CXA16/CXB16 multiplexors supported.

Beta Tested RSTS/E and VMS Compatibility Guide available-about 900 pages of useful information on incompatibility issues.

Ken Surplice, European Marketing Manager, hosts “PDP-11 Commitment, Development and Performance” Seminar.

June-Computer Craft (founded by Steve Gray) announces the new BP3 Compiler that produces directly executed code which runs Basic Plus programs three times faster.

September-RSTS/E Version 9.6 is released. It includes LAT support for interactive terminals-but not for printers. In addition, a few new useful commands, such as HELP SPIKE.

October-Anaheim Session notes on performance state that “although no one realized it at the time, the extra overhead caused by the cross-phase calls between DUDSK and the common code modules CPH and UQPORT was enough to slow throughput on MSCP disks- drastically under some circumstances”.

October-In a RSTS 18th Birthday Review, total sales, and word length, of all systems sold at this point:

PDP-1                      18                   100

PDP-4                      18                     40

PDP-5                      12                   100

PDP-6                      36                     21

PDP-7                      18                   100

PDP-8                      12              50,000

PDP-11                    16            600,000

PDP-12                    12                1,000

VAX                         32            150,000

November-“The Ultimate Entrepreneur”, written by Glenn Rifkin and George Harrar, starts with the words “Ken Olsen didn't want this book written”.



May-Digital and N.D.S. sign joint Co-operative Promotional Agreement with regard to The LINK.

May-Atlanta Session Notes contain almost 100 pages including the following note: “Currently there is no penalty for missing one or more of our sessions-although we are suggesting various punitive measures to the RSTS/E SIG for their consideration”.

June-Vernon Miller gives full day RSTS Seminar in the U.K.

July-RSTS/E Version 9.7 announced. INIT now recognizes DR11 and DRV11 interface boards. Virtual Disk is now created under timesharing and becomes the worlds first RAM disk capable of returning message “?Device hung or write locked”. EDT benefits from significant performance improvements.

September-Both WPS-PLUS and UTOPIA systems fail-the software uses an incremental day counter (with day 1 being 01-Jan-1900) and 15th September is day 32767...

October-Digital Australia announce an innovative $20 PDP-11 Home Operating System Licence, available only to DECUS members, that gives “a warm feeling of legality and the ability to speak openly about a home system”.



VT1000 X-window terminal announced-still no E-window support for RSTS/E users.

DATATRIEVE-11 Version 3.3A now displays the decimal point in the correct position.

March-Ken Surplice, Richard Holloway and Paul Goodwin give “Back To The Future” presentation at DECUS UK Conference.

Numeric list of 26 processors to date includes:-

11/02, 11/03, 11/04, 11/05, 11/15, 11/20, 11/21, 11/23, 11/23-Plus, 11/24, 11/34, 11/34A, 11/35, 11/40, 11/44, 11/45, 11/50, 11/53, 11/53-Plus, 11/55, 11/60, 11/70, 11/73, 11/74MP, 11/83, 11/84.

April-EG&H celebrate 20 year anniversary and continue to supply KDSS and TAM (winner of an IPC million dollar award) in addition to COLINK, FSORT3 and SELECT.

PDP-11 “C” Version 1 now being shipped. It conforms to the ANSI standard-at least with regard to its name.

May 7th-PDP-11/93 announced on the first day of the DECUS Symposium in New Orleans. It is rated 40% faster than an 11/83 and features up to 4Mb of on board memory (using 4Mbit chips) with eight serial lines.

RSTS/E Version 10.0 announced.

It contains a massive number of enhancements-including ECHO ON READ character handling to give the “look and feel” of VMS. (However, RSTS systems still retain faster response times.)

May 9th-RSTS 20th Birthday celebrated with party at DECUS Symposium.

July-SPL announces special anniversary “offers” on various software products including The Link, BAS24K, BP3, RPM, DECOMP, SORT1 and REPGEN.



Kenneth H. Olsen (Founder and 1st President) almost retired on 20th February (65th birthday) having master-minded the Apple take over.

1,000,000th PDP-11 installed-it formed part of the Digital internal Order Administration System that was still running under RSTS/E.



The announcement of P90 (Processor for the 90s) system based on new PDP-11 system marks the decline of the VAX range.

Digital now claims “One family, One system” was always meant to refer to the PDP-11 family.

RSTS Version 11 allows for all 3 dates to be associated for a file: created, last accessed and last updated. (This item had been on the wish list for over 15 years.)

True DCL compiler introduced.

Job Max is increased to 127 Jobs-although no new hardware is available to support the extra users.

Maximum number of keyboards increased to 255.

New features added to Basic Plus include DATE% and RAD% functions, together with line numbers increased to 65535.

Quantic announces UNIX Run Time System for use under RSTS/E.



RSTS Version 12 announced with support for SMP (Symmetric Multi-Processing).

It included a new multi-threaded FIP that ran in Supervisor mode.

Also included was a CACHE.DPY program that displays contents of both DIRECTORY and DATA CACHE.

Protection codes on UFD. File description block added (max 39 bytes per file). DIRECTORY/DESCRIPTION command added to DCL.

Access counts on files record number of times each file is opened, number of reads, number of writes.



ANSI standards require that the standard Basic Plus error message 105 “?What?” be recoded as “?No comprende”.

VAX renamed 90000 series after Number One seller of “Vacs” sues Digital to avoid problems with users buying the wrong product.

New DECtape 4, based on optical paper tape reader that senses round holes punched in the tape, now able to back up an entire 2 inch RA95 disk (1792 megabytes) in less than 20 miles.



RSTS 25th Birthday Party held during DECUS week 15-19 May, in Atlanta.

New PDP-11 processor, capable of running in compatibility mode, includes a subset of VAX machine code instructions within the user programmable microcode.



RSTS Version 14 supported new PDP-11/800 series systems, which are based on GaAs (Gallium Arsenide) G-11 processor.

Benchmarks show that the new CPUs run at 4.5 times the speed of PDP-11/70 and feature a new 24 bit memory management unit:

11/20                      16  bits       64 Kb

11/40                      18   "       256 Kb

11/70                      22   "           4 Mb

11/810                    24   "         16 Mb

PDP-800 series regarded as simple “upgrade” for VAX 9000 users.

New VMS to RSTS Migration Guide published-20,000 pages.

Porsche now claim that the “11” in 911 refers to PDP-11 chip which now tunes both the engine and radio.



The Channel Tunnel opens five years behind schedule. There were 15 bomb scares in the first week.

New 64 megabit memory chips now available at $5 each. ET11-first Digital line printer to actually stack the paper announced.

New DECshock office wiring system based on earth circuit of standard mains announced. Main advantage is that you only need one wire.



First prototypes of video phones based on PDP-11 (using new K-11 chips) now available at less than $100. This unit also incorporated both speech and fax circuits.



January-98% of all computer systems fail as the date 01-Jan-00 is sorted earlier than 31-Dec-99.

RSTS/E 30th Birthday Party held during DECUS week 8-12 May, in New Orleans.

RSTS/E supports new 1 millisecond, 1 gigabyte 1 inch disk drive that runs by solar power with a Mean Time Between Failure of 1 million hours. Sadly daily BACKUPs now take two days with TK30s.



RSTS documentation describes features that have existed since early 1980s but which have never been documented, ie:

NAME “TEST.DAT/SI:-1” AS “TEST.BAK” will always work, even if there is an already existing .BAK file which would otherwise have generated a “?Name or account now exists” error message.

In addition, at Option level, the command FILL SCOPE has always set the rubout characteristics to work correctly.

The newly formed “RSTS Real Time SIG” declares the definition of Real Time as “You're going to like this-didn't you”.



FINS-11, special military version of the PDP-11 developed for US Navy. It features both TUNABUS and OCTOBUS for high speed transfers, DECwet/E for communication via micro-fiche and, of course, a CORAL compiler. The whole system is mounted on special ten legged DECapod chassis.



Super cooled PDP-11 L-101 processor chip announced that supports a clock running at 256 megahertz.



September-21st annual corporate hiring freeze starts.



Jackie Carter (Caroline Kennedy's daughter) wins second term as President of the United States of North and South America.



First computer 100% designed and built by a PDP-11 artificial intelligence system resembles an early 11/45, complete with a FASTER-BUS and a CHEAPERNET.



Jeanne Davis celebrates 50 years with Digital and says that raising great grand children has added even more years to her age.



Robinsons Ripples allow the polarising of radio frequencies to be both multiplexed and magnetised in smaller waves (Ripples) which transmits data at 8 times the speed of light.

Vapournet becomes trade mark of Digital Press Office.



RSTS Version 20 allows for long site names (ie more than 14 characters) and supports a real time clock that doesn't require resetting each time power is lost from the system.



Panic sets in for users who had failed to realise that DATE$() routines only went from 01-Jan-70 to 31-Dec-35.



European standardization of clocks means the introduction of the decimal day and hour-RSTS/E now defaults to STAR format.



The UES (United European States) appoints its first President, Prince Albert-elder son of King William of England.



50th DECUS SIG formed, SLUG (Saturn Local User Group), mainly concerned with moon based lunartics hacking their systems and over-coming problems earthing their equipment.

Digital introduces training for Sales Engineers.

Corporate SNAP (Sales Nominal And Purchase ledgers) announced.



New PDP-11/900 series announced with 32 bit memory management unit. Range now comprises of:-

PDP-11/924            Unibus Entry model-being discontinued

PDP-11/944            Unibus Mid range

PDP-11/928            Top of the range

PDP-11/911            Fastest PDP-11 ever built



Martin Lomas, DEC UK High End Systems and Cabinet Colouring Manager, announced new scheme: “Using 32 bit State of the Art technology, we are now able to offer all VAXs in over 4 gigatints. In addition, old PDP-11 users will have access to a subset of 65,536 shades of grey and we are providing sprays to allow users to upgrade and recolour their systems”.



Later this year, on 11th June 2050 to be precise, the RSTS/E operating system will be 80 years old.

Way back in 1985, Version 9 introduced a 3rd date format, STAR, in addition to the long standing Alphabetic and numeric formats.

This was a key feature.

Not only did it “fix” the Birth of RSTS, since 11-Jun-70 is day 1 in STAR format, but also it was the first real sign that Digital expected RSTS to be around for a long, long time.

STAR date format doesn't run out until the year 2150-still another 100 years to go.

Digital has IT now... but we made it work.



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