Perspectives COMP1200 on Computing
Lecture notes by Brendan McKay
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History of Computing
What is a computer? What essential ideas preceded computer hardware? How did computing technology develop?
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Theoretical preliminaries (1)
The concept of an algorithm Babylonians (1st millenium BC) Euclid (Greece, 300BC) Sun Ts (China, ca. 300AD) u al-Khwrizm (Persian: Baghdad, ca. 800AD) a i
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Theoretical preliminaries (2)
Boolean logic George Boole (1815-1864) Many mathematicians (19th-20th centuries)
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Computing devices earliest
Abacus (Babylonia and China, before 500BC) Antikythera mechanism (150BC) Leonardo da Vinci's calculator (1500AD; disputed!)
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Computing devices first calculators
Slide rule (1621) Wilhelm Schikard's "calculating clock" (1623) Blaise Pascal's "arithmetic machine" (1642)
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Computing devices mass produced calculators
Gottfried von Leibniz's "step reckoner" (1670) Charles Xavier Thomas de Colmar's "arithmometer" (1820) Various similar mechanical calculators (1800s)
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Mechanical calculators galore
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Computing devices self-powered
Charles Babbage's "difference engine" (1822) Charles Babbage's "analytical engine" (1834) Scheutz & Son, working difference engine (1853)
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Table interpolation using differences
Many uses for tables of mathematical functions, eg. Astronomical tables (used in navigation) Artillery tables (used for shooting things)
x 6.0 6.1 6.2 6.3 6.4 6.5 f (x) 1.791759 1.808289 16260 1.824549 16001 1.840550 15748 1.856298 15504 1.871802 2008 10 COMP1200: lecture 17 -244 -253 9 -259 6 3 differences 16530 -270 11 -5 8
The concept of a program
Jacquard loom (1801) Augusta Ada Lovelace (1815-1852)
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Punched cards and paper tape
Charles Wheatstone's use of paper tape for telegraphy (1857) Herman Hollerith's use of punched cards for US census tabulation (1890)
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Computing devices mechanical relays
IBM 601 punched card machine (1935) Konrad Zuse, electro-mechanical computer Z1 (1938)
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Earliest modern computers
Atanasoff and Berry, special purpose electronic computers (19391941) Konrad Zuse, programmable computer Z3 (1941)
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First electronic computers (1)
Thomas Flowers' Colossus, first electronic computer (1943) Harvard Automatic Sequence Controlled Calculator (1944)
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First electronic computers (2)
ENIAC (Electronic Numerical Integrator Analyzor and Computer), Harvard 1946
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Stored-program computers
Idea dates from Zuse (1936), von Neumann (1946) Manchester SSEM "Baby" (1948) Manchester Mark I (1949)
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First Australian computer (CSIRAC)
Built at CSIR in Sydney in 1949, moved to Melbourne in 1955, ran until 1964 2000 valves, 768 words of memory, 4096 word magnetic drum, paper tape and teleprinter
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History of Computing
Computers of the immediate post-WWII period were:
Very large and heavy. Very expensive. Used many custom-made components. Had very little memory and very slow i/o.
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Commercial computers (1)
"I think there is a world market for maybe five computers." Thomas J. Watson, chairman of IBM, 1943.
"Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have only 1,000 vacuum tubes and weigh only 1.5 tons." Popular Mechanics, March 1949.
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Commercial computers (2)
Z4 (Zuse KG) - September 1950 Ferranti Mark I - January 1951 UNIVAC I (Sperry-Rand) - June 1951
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"Mainframe" computers
General-purpose computers were called "mainframes" from the 1960s. After smaller computers were introduced in the 1970s, the name "mainframe" continued to be used for large-scale computers. IBM 360 series (1965 onwards) Digital Equipment Corporation PDP series (1964 onwards) UNIVAC, Burroughs, Amdahl, Data General, etc
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Memory technologies
Mercury delay lines. Magnetic core memory.
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Switching technologies
Electric relays. Valves (vacuum tubes) 1940s. Transistors from 1959. Integrated circuits from 1964.
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Secondary storage technologies (1)
Magnetic tape. Magnetic drum. Magnetic disk.
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Secondary storage technologies (2)
Floppy disks (from 1969) Magnetic bubble memory (1970s, failed) Optical disks (from 1990s)
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Microprocessors
Intel 4004 (4-bit) 1971. Intel 8080 and Motorola 6800 (8-bit) 1974. Zilog Z80 1976. Intel 8086 (16-bit) 1978. Motorola 68000 (32-bit) 1980. Intel 80386 (32-bit) 1986. - predecessor of series that included Pentium, AMD, etc.
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Moore's Law (1)
In 1965, Gordon Moore predicted that the number of components on a chip would double every two years.
Source:Intel
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Moore's Law (2)
Other indicators that have exhibited similar growth behaviour:
Processor speed. Processor power per dollar. Capacity of hard disks.
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Moore's Law (3)
The end of Moore's Law has been predicted many times, so far incorrectly. However, there are serious future obstacles:
Components cannot be made smaller than atoms. Components too close together begin to interfere with each other. Quantum mechanics imposes limits on how far noise can be reduced, how uniform impurities can be, etc..
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Personal computers
Micral "microcomputer" (France) 1972. Altair, Tandy, Commodore, etc, 1970s. Apple II (1977), IBM PC (1981) mass market. Apple Macintosh 1984.
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History of the Internet (1)
Telegraph and telephone networks used "circuits" Packet switching theory ARPANET - defence network USA - (1969) initially only file transfer and remote login Email introduced to ARPANET (1972) TCP/IP protocol developed (19731974) - adopted by ARPANET in 1983
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History of the Internet (2)
Many networks: CSNET, BITNET, USENET, XNS, DECNet etc (late 1970s to mid-1980s) - JANET in the UK - ACSNET and CSIRONET in Australia
munnari!anucsd.oz![e-mail]
Dedicated Australia-ARPANET link (1989) First proposal for hypertext network (1989) Web browsers. First is "www"' (1991) Graphic web browsers. First is "Mosaic" (1993)
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History of the Internet (3)
How long will this trend continue?
Source:ISC/Wikipedia
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History of Computing
Computers are not much use without software.
Programming languages. Operating systems. Protocols and standards.
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Manual programming and machine code
Plugs and switches. Machine instructions expressed in binary/octal/hex. Mneumonics human-friendly machine instructions. Machine instruction 166D 306E Mneumonic LOAD (6D),R6 STORE R0,(6E)
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Assembly languages (1)
Symbols. Relocation. X: Y: DATA DATA 1234 0
LOAD X,R5 ADD #1,R5 STORE R5,Y The meanings of X and Y depend on where this is loaded into memory.
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Assembly languages (2) Macros
A macro is a shorthand for a sequence of instructions. ZERO MACRO A LOAD #0,R0 STORE R0,A ENDMACRO Now ZERO is equivalent to LOAD STORE #0,R0 R0,XYZ XYZ
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High-level languages FORTRAN 1957
FORmula TRANslation designed for science & engineering. Major new versions 1966, 1990. INTEGER X(1000) C DO 20 I=1,N IF (X(I).LT.MINX) MINX = X(I) IF (X(I).GT.MAXX) MAXX = X(I) 20 CONTINUE WRITE (6,300) MINX,MAXX 300 FORMAT(1X,5HMIN= ,I6,2X,5HMAX= ,I6)
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High-level languages COBOL 1959
COmmon Business Oriented Language. Important revisions 1968, 1974, 1985, 2002. 500-PROCESS. IF IN-VALUE < WS-MIN-VALUE MOVE IN-VALUE TO WS-MIN-VALUE. IF IN-VALUE > MAX-VALUE MOVE IN-VALUE TO WS-MAX-VALUE. READ IN AT END GO TO 900-FINISH. GO TO 500-PROCESS. 900-FINISH
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High-level languages ALGOL 1958
ALGOrithmic Language. Main version 1960. minx := x[1]; maxx := x[1]; for i := 2 step 1 until n do begin if x[i] < minx then begin minx := x[i]; end if x[i] > maxx then begin maxx := x[i]; end end
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High-level languages ALGOL's children
ALGOL was the paradigm block structured, imperative, procedural language. Noted descendants have been: PL/I. Pascal. Modula and Modula 2. ADA. C and C++. Java.
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High-level languages LISP 1958-1962
LISt Processing Language. (TH1 (LAMBDA (A1 A2 A C) (COND ((NULL A) (TH2 A1 A2 NIL NIL C)) (T (OR (MEMBER (CAR A) C) (COND ((ATOM (CAR A)) (TH1 (COND ((MEMBER (CAR A) Al) Al) (T (CONS (CAR A) Al))) A2 (CDR A) C)) (T (TH1 A1 (COND ((MEMBER (CAR A) A2) A2) (T (CONS (CAR A) A2))) (CDR A) C))))))))
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High-level languages LISP's children
LISP was the paradigm functional language. Noted descendants have been:
Scheme. Common LISP. APL Haskell. ML.
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Operating Systems - pre-1955
Prior to about 1955,there were really no operating systems at all. System software was limited to a few things like assemblers, and had to be loaded each time they were used. Computer users had the whole computer to themselves and the computer was idle (running nothing) most of the time.
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Operating Systems - 1955-1965
Computers ran batch operating systems. Computers had a specialist operator. Users submitted their "jobs" to the operator on punched cards. The computer wrote the program output onto paper, or maybe onto magnetic tape. Typically users could have a job run every few hours. Jobs consisted of programs (in assembler or a high level language) interspersed with commands in a command language, also called a job control language.
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Operating Systems - 1965-1985
Computers had multiprogramming operating systems. Many programs could be run together, enabling overlap of execution and i/o, for example. On-line access (access via a terminal instead of by punched cards) became commonplace. This required frequent context-switching of processes (called time-sharing). Terminals initially accepted only a command language similar to that previously used on punched cards, but eventually became more graphical. An early multiprogramming operating system was IBM's OS/360.
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Operating Systems - 1980-present
For most of this period there was a strong division of computers into "mainframes" (large fast computers that were too expensive for individuals) and "personal computers" (smaller slower computers for personal use). Operating systems for mainframes and personal computers reflected the different needs of those environments. A major addition in both worlds was the introduction of local networks (LANs).
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Operating Systems - personal computers
The most important have been the DOS/Windows stream for PCs and the MacOS stream for Macintoshes. DOS began as a simple operating system MS-DOS that could execute only one process at a time. MacOS was the first operating system to offer an entirely graphical view where a mouse, pull-down menus, etc were used to perform actions instead of a typed command. This was later copied by Windows. At first Windows was merely a program running under DOS, but eventually it became an operating system in its own right.
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Operating Systems - UNIX and Linux
UNIX was developed in the early 1970s as a multi-user multi-process operating system. Because of a very clean design and because it is mostly written in the high level language C, UNIX is very easy to port to other computers. UNIX has suffered from lack of standardization, causing many variants to arise. Two variants in wide use were Solaris and Linux. Linux is an open-source version of UNIX that has become popular for personal computers as well as larger computers.
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The future of computing?
?
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