CTSS - Compatible Time Sharing System

CTSS Compatible Time Sharing System

Sebastian Woinar

IBM 7094 at MIT

Area of a triangle

Area of a triangle

1 0 0 0 0 9 9 9 9 9 0 0 0 0 0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

IDENTIFICATIONSEQUENCEFORTRAN STATEMENT

PUNCHING INSTRUCTIONS

PUNCH

GRAPHIC PAGE OF

CARD ELECTRO NUMBER*

PROGRAM

PROGRAMMER DATE

* A standard card form, IBM electro 888157, is available for punching statements from this form

X28-7327-5Printed in U.S.A.FORTRAN Coding Form

CO

NT.

STATEMENTNUMBER

®

Key Punch Room

Punched Card

Punched CardZ(1) = Y + W(1)

Binary formated

VisionJohn McCarthy

Fernando José Corbató

Fernando José Corbató

IBM 709

IBM 709T/7090

Operating System

• FMS - FORTRAN Monitor System

• compile FORTRAN programs

• IBSYS

• compile FORTRAN, COBOL etc.

IBM 7094 configuration


Basic Cycle Time: 2.18 µSecsFloat. Pt Add Time: 4.36µSecs

IBM 709Console

John Kelly

Max Mathews

Hardware Problems• Different user programs (and supervisor) may interfere

with each other

• Input-output equipement may be initiated by a user and read words in on another user program

• Time sharing supervisor must be able to interrupt user program after a quantum of computation

• Large core memories (e.g.. a million words) would ease the system programming complications immensely since the different active user programs, systems programs could remain in core memory at all times.

Hardware Problems• Different user programs (and supervisor) may interfere

with each other

• Input-output equipement may be initiated by a user and read words in on another user program

• Time sharing supervisor must be able to interrupt user program after a quantum of computation

• Large core memories (e.g.. a million words) would ease the system programming complications immensely since the different active user programs, systems programs could remain in core memory at all times.

Memory Protection

Trap all input-output instructions

Time controlled interrupt

8 MB RAM ;-)

Programming Problems

• Supervisor should charge user usage accounting automatically

• Supervisor should coordinate all user input-output

• Good system programs tooling

Usage Problems

• Too large a computation or excessive typewriter output may be requested

• Since real time is not usage-time, supervisor must inform user

• Computer malfuntions must be expected

7094 Modifications

• Standard 60 cycle accounting and interrupt clock

• Memory boundary and relocation register

• 2nd 32,768 Core memory bank for the supervisor

• 7094 has become a two-mode machine

Supervisor

• Provided virtual machines

• 3 foreground machines which run 7094 instructions and could invoke supervisor services

• 1 background machine with tape access

• Scheduling

• Managed I/O

Memory protection• 32k memory is managed in 128 blocks of 256

words

• 3 7 Bit registers

• Protection check

base [ 5* 256 ]<= addr <= end [ 7 * 256 ]

base relo5 7 5

end

Instruction protection

• User mode: subset of 7094 instructions

• Memory access only to defined region by memory relocation and protection

• Certain instructions are forbidden and invoke protection trap

Instruction protection

• User mode: subset of 7094 instructions

• Memory access only to defined region by memory relocation and protection

• Certain instructions are forbidden and invoke protection trap

Privileged instructions

all I/O instructions (RDS, WRS, BSR, BSF, SDN, RUN, REW, etc)

all channel instructions (RCHx, LCHx, SCHx, etc)

all I/O transfer instructions (TEFx, TRCx, TCOx, TCNx)

plus and minus sense (+0760... and -‐0760...)

Scheduling algorithm

• Goal:

• optimize turnaround time

• minimize response time

Multi Level Feedback Queue

• Task is put into level l0 dependent on its actual size (calculation time)

• Execution time in level x is 2x quanta

• If task is not completed, it is put at the end of level x+1 queue

• MLFQ is preemptive

Simulator

TYPSET & RUNOFF

• TYPSET for creating and editing files

• High speed input mode

• Edit mode

• RUNOFF

• Control words in the text

• Line-length, indention, alignment

MAIL

• Described in Programming Staff Note 39

• Created file MAIL BOX in directory

• User has been informed about new mail

RUNCOM

• File-system file of commands to be executed in a batch

• Commands are usable like library subroutine

MAC Project

Quellen• REMINISCENCES ON THE HISTORY OF TIME SHARING

• Fernando J. Corbato, Marjorie Merwin Daggett, Robert C. Daley AN EXPERIMENTAL TIME-SHARING SYSTEM, Proceedings of Spring Joint Computer Conference, May 3, 1962

• R.M. Fano, The MAC system: a progress report, MAC-TR-12

• http://www.ibiblio.org/apollo/Documents/CTSS_ProgrammersGuide.pdf

• http://www.multicians.org/thvv/7094.html

• http://www.multicians.org/thvv/mail-details.html

• http://www.frobenius.com/7090.htm

• http://motherboard.vice.com/2011/2/17/watson-s-hardest-question-what-is-life--2

• http://u-tx.net/media/fano-on-ctss.png

• http://mason.gmu.edu/~tbell5/page2.html

• http://www-03.ibm.com/ibm/history/exhibits/storage/storage_1301.html

• http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP7090.html

• http://simh.trailing-edge.com/docs/ctss_hardware.pdf

• http://mit.edu/saltzer/www/publications/ctss/CC-244.html

• http://en.wikipedia.org/wiki/Daisy_Bell

Simulator

• http://www.cozx.com/~dpitts/ibm7090.html

Videos

• http://www.youtube.com/watch?v=Q07PhW5sCEk

• http://www.youtube.com/watch?v=8edfFH0rklc

http://motherboard.vice.com/2011/2/17/watson-s-hardest-question-what-is-life--2


































CTSS - Compatible Time Sharing System

Documents

Transcript of CTSS - Compatible Time Sharing System