A Brief* History of Computers *I'm leaving out a lot, believe me...

A Brief* History of Computers

*I'm leaving out a lot, believe me. . .

First, what is a computer?• During WWII, people who performed

calculations (sometimes with adding machines or slide rules) were known as computers.

• These days, a reasonable definition is: an electronic device that stores, retrieves, and processes data, and can be programmed with instructions.

• For our purposes here, let's say that a computer is some sort of programmable mechanical or electronic device that helps people do calculations or otherwise process information.

Really, Really Early Computers

• The Abacus (2400 BC?)

• Antikythera Mechanism (150-100 BC)

• Schickard's calculator

Jacquard's Loom (1801)

A loom controlled by punched cards, rather than by a master weaverLed to the Luddite rebellion in England (1811-1816 )Even now, people who are hostile to technology are sometimes called Luddites

Babbage's Analytical Engine

Charles Babbage (1792-1871) is known as the father of the computer. The analytical engine (a part of which is shown above) anticipated many of the features of a modern computer. He worked on it from 1837 to 1871, but it was never completed. Nothing equivalent came along again until the 1940s.

(information on the Analytical Engine is mostly from "The Cartoon Guide to the Computer" by Larry Gonick.)

Babbage's Analytical Engine:

ComponentsThe Analytical Engine had 4 major components:

The Mill was basically an adding machine. It could add, subtract, multiply and divide, accurate to 50 decimal places.

Input was via punch cards, like Jacquard's loom. The cards specified not only the numbers to be used, but also the instructions – what the mill should to with the numbers.

The Store: a set of 1000 "registers", each able to hold a single 50 digit number. The registers could be loaded from punch cards, or from results produced by the mill.

Output: the results of computations would be printed through an automated typesetter

Babbage's Analytical Engine:

Instruction SetEach punch card could cause one of the following things to happen:

•Input a number to the store•Move a number from the mill to the store•Instruct the mill to perform an operation•Input a number to the mill•Move a number from the store to the mill•Output a number from either the store or the mill

So a result from the mill could be stored temporarily, then returned to the mill when needed later.

Augusta Ada Byron, Countess of Lovelace – the First

ProgrammerShe wrote out sequences of instructions for the analytical engine – the first computer programs. She developed some fundamental concepts which are the basis for computer programs to this day:Subroutines: sequences of instructions that can be reused in different contexts.Looping: an instruction should exist to back up the card reader to a specific card, so that the sequence of instructions can be executed over and overConditional jump: the card reader should be able to skip forward or backward to another card IF some condition is satisfied – say, if two numbers in the store are equal.

If Charles Babbage is the father of the computer, it's fair to say that Ada Lovelace is the mother.

Hollerith Tabulating Machine

These were created for the 1890 census. They led to the first commercial data processing machines. . . And this was the beginning of IBM.

Ballistics problem:• Mark I (Relays)• ENIAC (Vacuum tubes)

Code breaking:• Colossus (Vacuum tubes)

WW II and Computers

Relays and Vacuum Tubes

Vacuum tubes are electronic devices that can also be used to to switch

electrical currents on and off. They are about 1000 times faster than relays, but

use lots of energy, generate lots of heat, and can burn out. Originated in early

1900s.

Relays are mechanical switches controlled by electromagnets. They are very reliable, cheap, and use little power, but are slow compared to electronic devices. Invented in 1835.

Harvard/IBM Mark I - 1944

• Influenced by Babbage's Analytical Engine• Could do 3 additions or subtractions per second, and multiply

two 10 digit numbers in 3 seconds.• Programmed via punched paper tape.• Electromechanical - very reliable, compared with electronic

machines of the era. In use until 1959

ENIAC (Electronic Numerical Integrator

and Computer)

• Commisioned in 1943, unveiled in 1946• 1000 times faster than electromechanical machines• "Programmed" by rewiring it• Contained about 17,500 vacuum tubes, 1,500 relays, and 5

million hand-soldered joints.

Colossus

Bletchley Park

• 10 machines built• Automatically searched for

decryption keys• Reduced the time to break Lorenz

messages from weeks to hours. • The first one became operational in

1944, but the machine’s existence was not made public until the 1970s

The 50s• During the 1950s, computers became faster, smaller, and cheaper.• The UNIVAC I (above) from 1951 could carry out about 2000 arithmetic

operations per second, with a memory of 12000 bytes. It cost about $1 million.• In 1953 there were probably about 100 computers in the world.• In 1956, IBM sold its first magnetic disk system. It used 50 24-inch metal disks,

with 100 tracks per side. It could store 5 megabytes of data and cost $10,000 per megabyte (I think. . . )

• By the end of the decade, transistors were replacing vacuum tubes in commercial computers. The first integrated circuit was invented in 1958.

• IBM's 7000 series, their first transistorized computers, came out in 1959.

SAGE(Semi Automatic Ground Environment)• Designed to defend against Soviet bomber attacks• A network of 24 ENORMOUS computers, connected to 100

radar stations around the country via telephone lines.• Each computer weighed 250 tons, and required a 3,000kW

power supply (enough to run 30,000 100 watt light bulbs) and contained 49,000 vacuum tubes. These were the largest computers ever built.

• Real-time rather than batch processing – had to respond to real life events, rather than just processing static data. Each of the computers could track up to 400 planes.

• Each center could support up to 150 operators, each with a graphical display and "light gun" pointing device – very advanced for the era.

• 7000 programmers involved. Estimated cost was between $8 and $12 billion (in 1964 dollars)

• Operational from the late 50s through the early 80s.

A SAGE building

Operator consoles

Part of one of the computers Magnetic core memory

Transistors and ICsTransistors can serve as switches in digital circuits, much like vaccuum tubes. But they are smaller, cheaper, require less power, and are more reliable. The transistor was invented in 1947, at Bell Labs. The first transistorized computer was TRADIC, in 1954.

The integrated circuit (IC) was invented by Jack Kilby of Texas Instruments in 1958. Using photographic methods, many transistors and other components can be built up on a chip, layer by layer. The components on the chip are connected to one another by conductors within the chip itself, rather than external wires. Current state-of-the-art chips have transistors so tiny that 2000 of them fit in the width of a human hair, and 30 million on the head of a pin. IBM’s new Power6 chip has 700 million transistors.

The 60s • During the 1960s, computers became faster, smaller, and cheaper.

• Spacewar!, the first videogame, was written at MIT in 1962 to run on a Digital Equipment PDP-1.

• Computers started to use integrated circuits in 1964

• In 1964, IBM announced the System/360, a family of computers and peripherals that could work together. It was enormously successful, with orders for 1,000 per month within two years of the introduction. Computers started generating more money than punch-card systems for the company.

• The Digital Equipment PDP-8, the first commercially successful minicomputer, was introduced in 1965. The smallest one had the equivalent of 6K of memory, and could carry out about 330,000 instructions per second. It sold for about $16,000.

Mainframe Computers. . .

• . . . are big, expensive, reliable, fast machines that do bulk data processing, for things like accounting and billing, census data, and financial transaction processing.

• IBM has long dominated this business.

Minicomputers. . . • . . . first emerged in the 60s –

smaller and cheaper than mainframes

• Generally ran multi-user or real-time operating systems

• The minicomputer industry grew up in Massachusetts, around MIT.

• Major companies included Digital Equipment (aka DEC, the second largest computer company in the world in the late 80s), Data General, Apollo Computer, Wang Laboratories, and Prime Computer. They're all gone now.

Doug Engelbart and the

Mother of All Demos

• The mouse• Hypertext (the basis for the web)• Computer-based

videoconferencing,• Full-screen document editing• Copy and paste functions, • Context-sensitive help• Networked document collaboration• E-mail• Instant messaging

This was in December of 1968!

Doug Engelbart was one of the first people to realize that computers could augment people – help them do their work – rather than replace people by automating tasks. He gave a live demo of his online system, NLS, at the Joint Computer Conference in 1968 in San Francisco. That day he demonstrated:

Xerox PARC(Palo Alto Research Center)

Xerox Alto, 1973 – an early minicomputer, the first to use a GUI

and desktop metaphor

Their innovations in the 70s include:

• GUI with windows and icons• WYSIWYG text editing• Ethernet• Laser printing• and many other things. . .

They were 20 years ahead of their time. . . Steve Jobs took a lot of the ideas for the Apple Lisa and Mac from things he saw at Xerox

The First Personal Computers

The Altair 8800 is commonly regarded as the beginning of the personal computer era, in 1975. It was sold as a kit for $595, with an 8080 processor running at 2 Mhz, and 256 bytes of memory. As sold, It had no keyboard – programs and data were input through switches on the front, and output was via blinking lights. Additional memory and devices could be added.

Bill Gates and Paul Allen started Microsoft to write

software for the Altair.

Some Elderly PCs

Compaq Portable, 1983 $3500. 4.77 Mhz 8088 processor, 128K of RAM. Weighed 28 pounds – no battery, you had to plug it in.

Apple II – 1977 $1298 with 4K RAM, $2638 with 48K RAM. 1 Mhz 6502 processor.

Apple Macintosh Portable: 1989 $7300 w/ hard drive. 16 Mhz 68000 processor, 1 Meg memory. Weighed 16 pounds, including battery

Apple Macintosh, 1984$2495 with 128K RAM, 7.83 Mhz 68000 processor

IBM Personal Computer, 1981$3000 with 16K memory, 4.77 Mhz 8088 processor,No hard drive

• IBM Personal Computer, 1981: $3000 with 4.77 Mhz Intel 8088 processor, 16K memory, monochrome monitor (no graphics), no hard drive

Moore's Law

•Dell XPS 720 Red Computer, 2007: $2949 with 3 Ghz Intel Core Duo processor,

2 GB memory, 160 GB hard drive

My, How They've Grown. . .

IBM Personal Computer, 1981

$3000 with 4.77 Mhz Intel 8088 processor, 16K memory,

monochrome monitor (no graphics), no hard drive

Dell XPS 720 Red Computer, 2007$2949 with 3 Ghz Intel Core Duo processor, 2 GB memory, 160 GB hard drive