The First Operating System Was Human

Transcription

1 The First Operating System Was Human CS 333 Professor Karavanic Lecture 1 1. What is an Operating System? Historical View 2. Course Information 3. What is an Operating System? Operating Systems Goals and Functionality

2 History of Operating Systems (0) Charles Babbage ( ) and Ada Lovelace: Analytical Engine 1821: Difference Engine No. 1: add, subtract, solve polynomial equations Required 25,000 precision-crafted parts Difference Engine No. 2: Simpler version Analytical Engine: multiplication, division, algebra 2

3 History of Operating Systems (0) 1990: Science Museum in London builds Difference Engine No. 2 in one year Cost: $500,000 Weight: three tons Size: 11 feet long, 7 feet tall Calculated successive values of seventh-order polynomial equations containing up to 31 digits Proves Babbage s design 3

4 Now at the Computer Museum in San Jose 4

5 History of Operating Systems (1) First Generation Computing ( ) 5 Goal: compute trajectories for warfare Relays/vacuum tubes (about 20,000)

6 History of Operating Systems (1) 6 Programming: plugboards Operating System: none Innovation: punch cards

7 The Eniac 7

8 History of Operating Systems (2) Second Generation Computing ( ) Innovation: transistors, mainframes Innovation: first compiler (Fortran) Batch systems Programming: Fortran, assembly language Operating Systems: FMS, IBSYS 8

9 History of Operating Systems (2) Early batch system bring cards to 1401 read cards to tape put tape on 7094 which does computing put tape on 1401 which prints output 9

10 History of Operating Systems (2) 10 Structure of a typical FMS job 2 nd generation

11 Simple Batch Systems Are the first operating systems (mid-50s) The user submit a job (written on card or tape) to a computer operator The computer operator place a batch of several jobs on a input device A special program, the monitor, manages the execution of each program in the batch Resident monitor is in main memory and available for execution Monitor utilities are loaded when needed 11

12 The Monitor Monitor reads jobs one at a time from the input device Monitor places a job in the user program area A monitor instruction branches to the start of the user program Execution of user program continues until: end-of-pgm occurs error occurs Causes the CPU to fetch its next instruction from Monitor 12

13 Job Control Language (JCL) Is the language to provide instructions to the monitor what compiler to use what data to use Example of job format: >> $FTN loads the compiler and transfers control to it $LOAD loads the object code (in place of compiler) $RUN transfers control to user program $JOB $FTN... FORTRAN program... $LOAD $RUN... Data... $END 13

14 Job Control Language (JCL) Each read instruction (in user pgm) causes one line of input to be read Causes (OS) input routine to be invoked checks for not reading a JCL line skip to the next JCL line at completion of user program 14

15 Batch OS Alternates execution between user program and the monitor program Relies on available hardware to effectively alternate execution from various parts of memory 15

16 Desirable Hardware Features Memory protection do not allow the memory area containing the monitor to be altered by user programs Timer prevents a job from monopolizing the system an interrupt occurs when time expires 16

17 Desirable Hardware Features Privileged instructions can be executed only by the monitor an interrupt occurs if a program tries these instructions Interrupts provides flexibility for relinquishing control to and regaining control from user programs 17

18 History of Operating Systems (3) Third Generation Computing ( ) Innovation: integrated circuits Innovation: multiprogramming Innovation: timesharing Innovation: minicomputers (DEC PDP-#) Programming: Fortran, Cobol, PL/1 Operating Systems: OS/360, CTSS, MULTICS, UNIX 18

19 History of Operating Systems (3) Multiprogramming system three jobs in memory at once 19

20 Multiprogrammed Batch Systems I/O operations are exceedingly slow (compared to instruction execution) A program containing even a very small number of I/O ops, will spend most of its time waiting for them CPUs had only one core did only one thing at a time Hence: poor CPU usage when only one program is present in memory 20

21 Multiprogrammed Batch Systems If memory can hold several programs, then CPU can switch to another one whenever a program is awaiting for an I/O to complete This is multitasking (multiprogramming) 21

22 Requirements for Multiprogramming Hardware support: I/O interrupts and (possibly) DMA in order to execute instructions while I/O device is busy Memory management several ready-to-run jobs must be kept in memory Memory protection (data and programs) Software support from the OS: Scheduling (which program is to be run next) To manage resource contention 22

23 Time Sharing Systems (TSS) Batch multiprogramming does not support interaction with users TSS extends multiprogramming to handle multiple interactive jobs Single core Processor s time is shared among multiple users Multiple users simultaneously access the system through terminals 23

24 Time Sharing Systems (TSS) Because of slow human reaction time, a typical user needs 2 sec of processing time per minute Then (about) 30 users should be able to share the same system without noticeable delay in the computer reaction time BUT The file system must be protected (multiple users ) 24

25 History of Operating Systems (4) Fourth Generation Computing (1980-?) Innovation: [Very] Large Scale Integration ([V]LSI) Innovation: microcomputers / PCs Innovation: GUI (XEROX), X Innovation: fast networks, internet, WWW Programming: Fortran, assembly language Operating Systems: CP/M, DOS, Windows, Linux 25

26 History of Operating Systems (5) Leading to Present Time (? 2015) Mobile devices Innovation: Fast Pervasive wireless and cellular Innovation: Power Management Embedded Systems Is your car on the internet? Your toaster? Open Source Virtualization Innovation: New HW support for Virtualization Cloud Computing Multicore and Manycore Processors disruptive technologies 26