History of Electronic Computers

1642–1945 Mechanical Era

1946– Electronic Age: divided into 4/5 generations

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Key Developments/Relationships

George StibitzBell Labs (USA)1937−43

Mark I, IIHoward AikenHarvard/IBM (USA)1939−44

Cryptanalytic Machines(not much info, classified)* special purpose, plugboards & switches* COLOSSUS (1943) allied code−breaker

ENIACJ.P. Eckert &J.W. Mauchly1946

Z1, Z3Konrad Zuse(Germany)1938−41

EDVACJ. von NewmannPrinceton1946−52

EDSACM.V. WilkesCambridge (England)1947−49

ACEA. Turing1946−47

History

Electromechanical Electronic

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Electromechanical Systems

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Konrad Zuse

I worked independently of England and U.S.

I Z3 (1941): first operational, program controlled, computer

I pgm control: tape, 8 bits/command

I arithmetic unit: binary, floating point, word length 22-bits(sign, 7-bit exponent, 14-bit mantissa), builtin operations: +,-, ×, ÷, square root, times (2, .5, 10, 0.1, -1)

I store: 64 words

I output: lamp display w/ 4 decimal places and decimal point

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Zuse (continued)

I Z3 destroyed in 1944 air raid

I believed to have independently developed ideas of:

I binary arithmetic — Liebniz

I program control — Babbage

I instruction formats — Ludgate

I floating point representation — Torres

I lacked idea of conditional branch

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H. Aiken (Grace Hopper)

I Mark I (1940–1944)

1. Decimal Arithmetic

2. punched paper tape for program control

3. 2-address instructions

I Mark II (1944–1947)

1. floating point numbers

2. multiple arithmetic units, usable simultaneously

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Stibitz

I Complex Computer (1938–1940)

1. complex numbers: +, -, ×, ÷

2. binary arithmetic

3. automatic decimal/binary conversions

I Relay Interpreter (1939–1943)

1. BCD number representation

2. Error detecting codes

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Electronic Computers: Instantiation

John Atanasoff (1939):applied mathematician, Iowa State Univ

I designed special purpose machine to solve “large”systems of linear equations

I claims to be first with operational electronic computer,largely unrecognized

J.P. Eckert and J. Mauchly

I Moore School of Electrical Engineering, Univ ofPennsylvania

I ENIAC (1945)I first general purpose computerI not stored program

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ENIAC

1. Vacuum tube technology (18,000)

2. decimal computer

3. 20 word memory (A1, A2, ..., A20) called accumulators

4. word size, 10-digits

5. programmed by manual switches/plugboards

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EDVAC (1945–1951)

First stored program computer design, conceived becauseENIAC:

I difficult to programI limited memory capacityI slow memory access

First draft report of EDVAC written by John von Neumann in1945; therefore he is credited w/ developing stored programconcept.

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Moore School Lectures (summer 1946)

Moore School LecturesSubject: EDVAC

Eckert & MauchlyBINAC (1950)UNIVAC (1951) (taken over by Sperry Rand Co; for several years was undisputed leader of U.S. computer market)

EDSAC (1949)M.V. WilkesCambridge U.

IAS (1952)J. von NeumannInst. for Advanced Study

EDVAC (1951)(built by others at Moore School)

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Major Generations in the

Evolution of Electronic Computing

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First Generation (1946–1954)

Technology: vacuum tubes, acoustic/CRT memories

Hardware/Arch: centralized control, fixed point arithmetic

Software: assembly languages

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First Generation: Examples

I EDSAC (1949) Cambridge U.I memory hierarchy (primary memory to drum)I floating point emulators provided as system routines

I ISA (1952) PrincetonI CRT memory allowing entire word access as one operation

I Whirlwind I (1951) MITI ferrite core memory

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First Generation (cont)

I UNIVAC I (1951)I magnetic tapes w/ ability to read fwd/bkwd, and w/ buffering

and error checking capabilities.I because of slow mercury delay line memory was rapidly

replaced w/ ferrite core based UNIVAC II (1957)I first successful computerI Grace Hopper: Mathematic→ Algol, Flowmatic→ COBOL

I IBM 701 (1953)I disk and tape secondary memories

I MADM (?) Manchester U.I index registers

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First Generation (cont)

I IBM 704 (1955)I hardwired floating point arithmetic (first)I indirect addressing (first)

Memory sizes in this era will still quite limited. Therefore, somemachines were constructed with drum memories (e.g., IBM 650(1954)). Because of slow access, the assembly operationswere place at strategic points on drum — at first by hand, laterby programs (e.g., SOAP).

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Second Generation (1955–1964)

Occurred primarily due to technological advances (transistor).

Technology: discrete transistor, ferrite core memories, magneticdrums.

Hardware/Arch: floating point arith, index registers, I/Oprocessors.

Software: High Level Languages (FORTRAN, COBOL, ALGOL,LISP), system software (e.g., compilers, subroutines libraries,batch monitors).

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Second Generation: Examples

I UNIVAC 1103 (1956)I floating point hardwareI program interrupts (first)

I IBM 709 (1959)I hundreds sold at several million dollars each

I IBM 1401 (1961)I 20,000 sold

I Honeywell H-800 (?)I replaced 1401 w/ movement to S/360

I IBM 7094 (?)I data channels

I EDSAC II (?)I micro-programming (first)

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Second Generation (cont)

I CDC 6600 (1964)I multi-functional units

I Burroughs B-5000 (1963)I designed to efficiently support Algol-60 (first lang directed

arch)I Atlas (1962) Manchester U.

I virtual memory (first)I IBM Stretch (1961)

I attempted to push state-of-the-art to the limitI instr. lookahead and partial executionI interleaved memoryI hardware support for protecting multiprogrammed tasks

I Burroughs D-825 (1962)I first multiprocessorI 2 processors connected to 16 memories (crossbar)

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Second Generation (cont)

This generation also sees the introduction and widespread useof HLLs (high level languages):

FORTRAN (54–57)

ALGOL (58–62) introduction of BNF

COBOL (59–60) DOD enforced as standard

LISP (60–65) MIT

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Third Generation (1965–1975)

Caused primarily by:

1. development of SSI and MSI integrated circuits,2. generalized use of micro-programming to implement

instruction sets, and3. the generalization of multiprogrammed operating systems.

Technology: integrated circuits (SSI, MSI), semiconductormemories

Hardware/Arch: micro-programming, pipelining,multiprogramming, multiprocessing

Software: timesharing, virtual memory, O/S

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Third Generation: Examples

I CTSS (early 1960’s) MITI time sharing

I IBM S/360 (1965)I architecture familyI micro-programming

I MU 5 (?)I pipelining

I ILLIAC IVI array processing (4 quadrants of 64 processors; only 1

quadrant built)

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Notes for 3rd Generation

multiprogramming: overlapped execution of different pgms w/ 1CPU

timesharing: multiprogramming system that allows for manyinteractive users

multiprocessing: machines that provide for concurrentexecution of programs by multiple CPUs

SSI ∼ 10 gates/chipMSI ∼ 10-100 gates/chipLSI ≤ 10,000 gates/chip

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Fourth Generation

Technology: LSI, VLSI, bit-slice logic

Hardware/Arch: large scale multiprocessors, multicomputers,language directed architectures (including RISCs), distributedsystem architectures (including LANs), fault tolerant processors

Software: distributed operating systems, advanced compileroptimization techniques, electronic mail networks, concurrentHLLs

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Fourth Generation: Examples

I SYMBOL (1971) FairchildI HLL directed architecture (SPL)I migration of virtually all s/w (including compiler) into h/wI only one built

I C.mmp (1977) CMUI multiprocessor (16 PDP-11’s connected by crossbar to

16MM)I Cm* (1979) CMU

I multicomputer (interconnected clusters of processors; eachprocessor has own memory; hierarchical communicationstructure)

I Intel iAPX 432 (1980)I 2 VLSI chips with 160,000 transistorsI load balancingI object oriented arch

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Fourth Generation (cont)

I HP 3000 (?)I stack machine

I Burroughs B1700 (?)I multiple-language directed architecture (COBOL, RPG,

FORTRAN, Basic, and SDL)I bit addressable memory (length specified); variable size

ALUI dynamically swappable micro-programI on low end machines, micro-program resides in MM

I RISC I, II (1982, 1983) BerkleyI MIPS (1982) StanfordI IBM 801 (1982)

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Significant Publications:

Leading to Quantitative Analysis for Systems Design

I D. E. Knuth, “An empirical study of FORTRAN programs,”Software: Practice and Experience, 1 105–133, 1971.

I Manolis G. H. Katevenis, Reduced Instruction SetComputer Architectures for VLSI, 1985.

I J. L. Hennessy and D. A. Patterson, ComputerArchitecture: A Quantitative Approach, Morgan KaufmannPublishers, Inc., San Mateo, California, (all editions).

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Further Readings

I Randell, B. (ed), The Origins of Digital Computers, 1975.I Shurkin, J. Engines of the Mind, 1985.I Wilkes, M.V. Automatic Digital Calculators, 1956.I Annals of the History of Computers.I Rosen, S., “Electronic Computers: A Historical Survey,”

ACM Computer Surveys, Vol 1, No 1, 7–36, March 1969.

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