Evolution of Computers

Computer Programming I

EVOLUTION 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