History of Computers

COMPUTER PROGRAMMING I

History of Computers

Mechanical Devices

Pascaline (1642) Set of gears, similar to clock Only performed addition

Stepped Reckoner Gottfried Leibniz Cylindrical wheel with movable

carriage Add, subtract, multiply, divide,

square roots Jammed/malfunctioned

Mechanical Devices

Difference Machine (1822) Charles Babbage Produce table of numbers used

by ships’ navigators. Never built

Analytical Machine (1833) Perform variety of calculations

by following a set of instructions (or program) on punched cards

Never built Used as a model for modern computer

Mechanical Devices

Babbage’s chief collaborator on the Analytical Machine was Ada Byron.

Ada Byron Sponsor of Analytical Machine One of first people to realize its

power and significance Often called the first programmer

because she wrote a program based on the design of the Analytical Machine.

Electro-Mechanical Devices

Hollerith’s Tabulating Machine Herman Hollerith – used electricity For US Census Holes representing information to

be tabulated were punched in cards Successful

Mark I (1944) IBM & Harvard Mechanical telephone replay switches to store

information and accepted data on punch cards. Highly sophisticated calculator - unreliable

The Mark 1

Electro-Mechanical Devices

These devices were not mass produced.

Not Reliable

Still took time Hollerith’s machine took 6 years for a general

account.

Mark 1 – 51 ft. long, weighed 5 tons

First Generation Computers

Atanasoff-Berry Computer (ABC) Built b/w 1939-1942 Used binary number system Vacuum tubes Stored info by electronically burning holes in

sheets of paper.ENIAC

Electronic Numerical Integration and Calculator 1943, 30 tons, 1500 sq ft., 17,000+ vacuum

tubes Secret military project during WWII to calculate

trajectory of artillery shells. Solve a problem in 20 min that would have take

a team of mathematicians three days to solve.

What is a Computer?

An electronic machine that accepts data, processes it according to instructions, and provides the results as new data.

The Stored Program Computer

Alan Turing & John von Neumann Mathematicians with the idea of stored programs

Turing Developed idea of “universal machine” Perform many different tasks by changing a program

(list of instructions)Von Neumann

Presented idea of stored program concept The stored program computer would store computer

instructions in a CPU.

The Stored Program Computer

Von Neumann, Mauchly and Eckert designed & built the EDVAC (Electronic Discrete Variable Automatic Computer) and the EDSAC (Electronic Delay Storage Automatic Computer) Designed to solve many

problems by simply entering new instructions stored on paper tape. Machine language (1’s & 0’s)

The Stored Program Computer

Mauchly & Eckert built 3rd computer (UNIVAC - UNIVersal Automatic Computer) 1st computer language – C-10 (developed by Betty

Holberton) Holberton also developed first keyboard and numeric

keypad First UNIVAC sold to US Census Bureau in 1951

Second Generation Computers

1947, Bell Lab (Shockley, Bardeen, Brittain) Invented the transistor

Replaced many vacuum tubes Less expensive, increased

calculating speeds

Model 650 (early 1960s) IBM introduced first

medium-sizedcomputer (Model 650)

Still expensive

Second Generation Computers

Change in way data was stored

Magnetic tape and high speed reel-to-reel tape machines replaced punched cards

Magnetic tape gave computers ability to read (access) and write (store) data quickly and reliably

Third Generation Computers

Integrated circuits (ICs) – replaced transistors Kilby and Noyce – working independently developed

the IC (chip)

ICs Silicon wafers with intricate circuits etched in their

surfaces and then coated with a metallic oxide that fills in the etched circuit patterns

IBM System 360 (1964) One of first computers to use IC

Mainframes

A large computer that is usually used for multi-user applications

IBM System 360 one of first mainframes

Used terminals to communicate with mainframe

Fourth Generation Computer

Microprocessor (1970) Hoff at Intel Corp, invented microprocessor Entire CPU on a chip Makes possible to build the microcomputer (or PC) Altair – one of first PCs 1975 Wozniak and Jobs designed and build first Apple

Computer in 1976 IBM introduced IBM-PC in 1981