Talk:Compatible Time-Sharing System

Page name

I thought about moving this to "Compaitble Time-Sharing System", and turning this into a disambig page, but I don't have the energy; the Cray system is so rare, and the MIT system so historic, I'm not sure it's the right move anyway. Noel 19:16, 3 Sep 2003 (UTC)

The system is best known by its abbreviation. I think having a disambiguation page where 99% of all people will go one way is pretty lame, so I think the current setup is the right way to go.

By the way, what was CTSS compatible with? I never could figure that out. [Ans: FMS; see article.]

CTSS was compatible in that it allowed both batch and interactive processing at the same time. Simsong (talk) 15:22, 3 September 2017 (UTC)

It also was compatible in that mostly-unmodified FMS jobs could be run on interactive CTSS sessions. Jamplevia (talk) 21:32, 18 February 2022 (UTC)

MIT started with FMS and modified and extended it. See Corbato, May 1983. -- Jamplevia (talk) 11:58, 11 April 2022 (UTC)

Time-stealing

Reminiscences on the History of Time Sharing, John McCarthy, 1983 -- [demo was performed c. 1957 - 1959] This demonstration was called time-stealing, and was regarded as a mere prelude to proper time-sharing. It involved a fixed program in the bottom of memory that collected characters from the Flexowriter in a buffer while an ordinary batch job was running. It was only after each job was run that a job that would deal with the characters typed in would be read in from the drum. This job would do what it could until more input was wanted and would then let the operating system go back to the batch stream. This worked for the demonstration, because at certain hours, the M.I.T. Computation Center operated at certain hours a batch stream with a time limit of one minute on any job.

This was on an IBM 704 without the "IBM real time package" which would have provided true interrupts.

Research in Computer Utilization Dean N. Arden 1958, discusses details.

The second sentence the in History section needs to be improved with this information. The existing sentence (Computers at that time, like IBM 704, were not powerful enough to implement such system, but at the end of 1958, MIT's Computation Center nevertheless added a typewriter input to its 704... ) is confusing to me like it says something can't be done nevertheless it was done. Jamplevia (talk) 01:19, 23 February 2022 (UTC)

Influence on ITS

File system

Many of the design features of the CTSS file system were later used in the design of the ITS file system, e.g. M.F.D. (FILE) master file directory, U.F.D. (FILE) user file directory, file name conventions consisting of two mono-case, six-letter-maximum-length, separated-by-blanks (spaces) format, e.g. HELLO MAD. The concept of symbolic links was also first in CTSS and then in ITS.

Commands

ITS commands that were designed after CTSS commands include LISTF.

The CTSS ADMIN command has a sub-command, SPY. ITS has OS for "output spy".

Jamplevia (talk) 23:05, 5 April 2022 (UTC)

Online Documenatation

INFO On-line Documentation of the Compatible Time-sharing System By Joel M. Winett · 1965 An on-line system for storing and retrieving information about the programs associated with the Compatible Time-Sharing System (CTSS) has been developed to be included as a CTSS command. same document available as MIT-ESD TDR-65-68 and MIT-LL TR-387

"A model of this information [on-line documentation] system has been implemented as a CTSS command program with the command name INFO. The system may be initiated as a console command or may be "chained to" from another program. If, when the INFO system is called, the NAME of a program is give as a command parameter, the documentation on that program will be printed, after which the system will call CHNCOM."

Jamplevia (talk) 15:11, 23 February 2022 (UTC)

Thanks, this is very interesting. The more well known hypertext INFO (on which GNU info was modeled) was preceded by a much simpler plain text INFO that could select between various types of information: INFO, ORDER, RECENT, or ERROR. No ITS hacker I asked remembered anything about this. Does it ring any bells with regards to the CTSS INFO? Lars Brinkhoff (talk) 17:35, 12 March 2022 (UTC)

@Larsbrinkhoff I found a PDF of Winett's INFO thesis.

On-line Documentation of the Compatible Time-sharing System Jamplevia (talk) 23:03, 12 March 2022 (UTC)

Thanks! I read it, and found one trivial similarity: CTSS INFO has D for "description", and ITS' old INFO has Altmode D. Lars Brinkhoff (talk) 07:33, 14 March 2022 (UTC)

The Textile Information Retrieval Program (TIRP)

A STUDY OF TEXTILE INFORMATION SYSTEMS 1970

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For those who may not be informed of the reason for this last conclusion, it is explained here. The M.I.T. Textile Information Retrieval Program (TIRP) operates within the context of a Compatible Time Sharing System (CTSS) resident in an I.B.M. 7094 computer. There is no equivalent computer in the Research Triangle area, those available being of the I.B.M. 360 series. The latter do not have the CTSS function and TIRP, as written, is therefore not compatible to them. At the time when this particular matter was under examination a rough estimate of the cost of rewriting the program to make it compatible was around $50,000. This estimate, however, was rather casual and would certainly be open to revision.

skip

Prior to each session with the console, attendance at each being from two to about six people, a short discussion was held in which the basic operational characteristics and command structure were discussed. These discussions included description of the connection between the console and the computer and some elementary aspects of the time-sharing environment of CTSS and how TIRP operated within this environment.

-- Jamplevia (talk) 18:00, 8 March 2022 (UTC)

Mary Elizabeth Stevens

Research and Development in the Computer and Information Sciences. Volume 2, Processing, Storage, and Output Requirements in Information Processing Systems: A Selective Literature Review 1970

"The CTSS environment consists of approximately 250 users whose individual load on the system varies from nearly zero up to the equivalent of several hours of IBM 7094 time per month."

Stevens cites An Analysis of Time-shared Computer Systems By Allan Lee Scherr, Ph. D. Dissertation, Rept. No. MAC-TR-18, 178 p. (M.I.T., Cambridge, Mass., June 1965)

Jamplevia (talk) 02:48, 9 March 2022 (UTC)

Reconstructed CTSS

A collection of tapes of listings of CTSS source code have survived. Two people have independently extracted source code from those listing and organized the extracted files in different ways. There are sections of the listings which neither of them has extracted. One of them is a security program which enabled administrators to trace an active CTSS user back to the location of their terminal.

Jamplevia (talk) 13:35, 15 March 2022 (UTC)

Languages

PL/1

DMR on alt.folklore.computers Mar 25, 1999 One could write and compile Multics PL/1 programs on CTSS and prepare a magtape to be could be carried across the room to the GE machine. (If I recall correctly, the CTSS command was approximately "636tape", where the 636 was an incorrect guess as to the numerology of machine naming.)

AED-0

AED-0 is ALGOL Extended for Design. A general purpose programming system including a compiler, source language debugging facilities, and a library of subroutines. The compiler is especially suited to system programming, but includes algebraic statements, recursive functions, and mixed algebraic expressions for general purpose programming as well. The compiler language is an extended form of ALGOL-60, minus multi-dimensional arrays.

AED-0 was used to write DYNAMO. Jamplevia (talk) 23:39, 25 March 2022 (UTC)

NONLIN, UTOPIA, PREDLIN, PREDOD, EXTRAP, SIGTST and PREDCT

Optimal Prediction of Stationary Time and Series Application in a Stock Market Decision Rule] thesis, Stuart Allen Rooney, 1965. Contains listings in MAD for those programs. -- Jamplevia (talk) 21:49, 9 April 2022 (UTC)

1967 MIT President's report

Report of the President 1967 Massachusetts Institute of Technology Bulletin Volume 103, Number 3, December, 1967

Highlights:

• Both of the IBM 7094 computers in current operation on our campus under the Compatible Time-Sharing Systems (CTSS) are overloaded.
• They are, nevertheless, the most sophisticated time-sharing computer systems in existence anywhere.
• We note that our faculty has experienced first hand, as no other faculty ever has, the potential offered by a time-shared computer capability. It wants more.
• A great many improvements and additions to CTSS have been implemented since that time - both hardware and software. In particular, many user-developed programs and subsystems of general interest have been published in the form of system commands for general use. Thus, the system's capabilities have grown considerably as a direct outgrowth of its use on the part of the community. The software facilities offered by the system to the community of users amount to approximately one million words of code, roughly equivalent to a 2,000 page book.
• The only major system improvement implemented last year was the automatic monitoring and control of performance. It involves a complex of programs which monitor various overload conditions and take appropriate actions for relieving them, such as dynamically reducing the maximum number of simultaneous users. See QLOAD MAD, it's a listing from a tape with several programs on it.
• Project INTREX (Information Transfer Experiments)

-- Jamplevia (talk) 19:38, 12 April 2022 (UTC)

1968 MIT President's report

Report of the President 1968 Massachusetts Institute of Technology Bulletin Volume 104, Number 3, December, 1968

Highlights:

• Use of a PDP-7 connected to CTSS for display processing.
• Advanced Remote Display Station (ARDS) connected to CTSS.
• Use of CTSS in West Berlin in 1964 via transatlantic connection. M.I.T.-T.U.B. (Technical University of Berlin) Symposium on Computers in Universities which will take place during the last two weeks of July, 1968. A plan was in place for T.U.B. to receive the first ARDS in time for the symposium.
• Project MAC starts charging money for CTSS resources (ten separate components of service) on the red machine January 2, 1968. MIT had already been charging money for CTSS time on the blue machine.
• MIT Computation Center was redesignated as the Information Processing Center.
• A batch-only IBM System/360 installation that includes a Model 65 and a Model 40 operating in an Attached Support Processor (ASP) configuration is deployed.
• More about Project INTREX (INformation TRansfer Experiments)
• Additional software including DISCOURSE (Architecture and City Planning), ADMINS (Political Science), DYNAMO (Management), AED (Electronic Systems Laboratory) and ICES (Civil Engineering).
• The Sussenguth chemical structure-matching algorithm was used for counting the relevant subgroups in the molecule. In tests on 43 compounds, the execution time on an IBM 7094 computer to search the compound structure for 56 common subgroups ranged from 1.07 to 10.33 seconds, depending on the complexity of the molecule.
• Programming Linguistics, 6.231 ... The special computer language PAL (Pedagogical Algorithmic Language) has been implemented on the 7094 CTSS (Compatible Time-Sharing Systems) system, and is being used as a basic part of the subject.
• ELIZA in retrospect.

-- Jamplevia (talk) 23:28, 12 April 2022 (UTC)