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

2. 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.

3. Really, Really Early Computers
The Abacus (2400 BC?)
Antikythera Mechanism ( BC)
Schickard's calculator
Abacus
Antikythera Mechanism believed to be an ancient mechanical calculator (also described as a "mechanical computer" designed to calculate astronomical positions. Other machines using technology of such complexity would not appear until the 18th century
Wilhelm Schickard seems to have built first calculator in 1623 – could add, subtract six-digit numbers, with a bell for seven-digit overflows – not programmable. Not well known at the time because he died of the plague soon after inventing it.

4. Jacquard's Loom (1801)
A loom controlled by punched cards – each row of the card corresponds to a row of the design. Each space in a row controls the position of a hook, which can be up or down, depending on whether or not a hole is punched. The loom is programmable in that it will produce different designs, depending on the set of cards that is loaded into it.
Before this, weaving was a highly skilled trade – but the Jacquard loom incorporated the master weaver's expertise into a machine – now it could be duplicated. The winners were those who could now get cloth with nice patterns for a cheaper price, and those who owned the looms. The losers were the weavers, of course – had been a secure, well respected profession.
The development of the Jacquard loom eventually led to the Luddite movement in England, starting in weavers destroying looms and other machinery to protest their loss of income and stature.
Machine breaking was made into a capital crime. (Lord Byron was one of the few upper class people to oppose this law – his daughter Ada is today recognized as the first programmer. . )
(Anecdote about TERESA "the bitch that's taking our jobs")
A loom controlled by punched cards, rather than by a master weaver
Led to the Luddite rebellion in England ( )
Even now, people who are hostile to technology are sometimes called Luddites

5. Babbage's Analytical Engine
Charles Babbage ( ) is known as the father of the computer.
He worked for several years on a mechanical calculator called the difference engine, which was never completed. When he learned about the Jacquard loom, he was inspired to create a new machine, called the analytical engine, which included many of the major features of a modern computer.
Was intended to be powered by steam
Charles Babbage ( ) 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.)

6. Babbage's Analytical Engine: Components
The 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
E.G., add A to B, then divide by C
Output: Babbage inspired by this

7. Babbage's Analytical Engine: Instruction Set
Each 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.

8. Augusta Ada Byron, Countess of Lovelace – the First Programmer
She 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 over
Conditional 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.
For instance, a subroutine might be used to find the square root of a number.
She was Lord Byron's daughter
Trying to raise money to build the machine, Babbage came up with a scientific racetrack betting scheme and squandered Ada's fortune

9. 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.
The first use of machines to process large volumes of information was the 1890 US Census – what had taken 7.5 years to process for the 1880 census was reduced drastically, to 2.5 years (sources differ on the number – some say 6 weeks!)
System based on punched cards – again inspired by Jacquard loom (Hollerith's brother in law was in the silk weaving business)
Technology was adapted by railroads, insurance companies, department stores (The New York Central RR alone processed nearly 4 million freight waybills a year. . . )
something different – before this, the calculating machines had always been concerned about doing arithmetic – but here they're not working with numbers in the same sense
cards represent info about something – a person, a family, etc
combining and processing these cards – tabulating – allows you to get the "big picture" – still involves arithmetic, but it's "data processing" in the modern sense, not just doing arithmetic

10. WW II and Computers Ballistics problem: Mark I (Relays)
ENIAC (Vacuum tubes)
Ballistics – how to aim artillery and bombs – complex calculations WWI Big Bertha shot 94 miles, twice as far as oversimplified calculations predicted
Bottom picture – Lorenz machine, used by Nazis for high-level military communications during WW II.
Code breaking:
Colossus (Vacuum tubes)

11. Relays and Vacuum Tubes
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.
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.

12. Harvard/IBM Mark I - 1944 Influenced by Babbage's Analytical Engine
51 feet long, 8 feet high, 2 feet wide
Had no conditional branch capability
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

13. ENIAC (Electronic Numerical Integrator and Computer)
military firing-table calculation, atomic-weapons design
During the 11 years ENIAC was online, it did more arithmetic than the entire human race had done up to (Wired)
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.

14. Colossus 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
British figured out how Lorenz machine worked by 1942 without ever seeing one, due to a mistake* by a German operator.
(*wikipedia: On 30 August 1941, a 4,000 character message was transmitted; however, the message was not received correctly at the other end, so (after the recipient sent an unencoded request for retransmission, which let the codebreakers know what was happening) the message was retransmitted with the same key settings (HQIBPEXEZMUG); a forbidden practice. Moreover, the second time the operator made a number of small alterations to the message, such as using abbreviations. From these two related ciphertexts, John Tiltman was able to recover both the plaintext and the keystream. From the keystream, the entire structure of the machine was reconstructed by W. T. Tutte.)
Allies weren't the only ones working on computers – German Konrad Zuse made some very advanced programmable digital computers starting in He was denied government funding because the work was deemed "strategically unimportant". Who knows what would have happened if he had been supported. . .
Bletchley Park

15. 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 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 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.
Hitachi 1 TB drive for 88.00
8.8 cents/GB
.0088 cents/MB
from $10,000/MB to under one hundredth of a cent! (

16. 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, 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.
Show first 7 minutes, skip to last minute of "on guard" video
Obsolete by the time it was first deployed - Not very helpful against ICBM attacks
fooled more than once by flocks of birds soaring above Newfoundland.
Some aspects of the technology survive in SABRE, the air reservations system

17. Part of one of the computers Magnetic core memory
Operator consoles
A SAGE building
Part of one of the computers
Magnetic core memory
each operator console was equipped with an integral cigarette lighter and ashtray.

18. Transistors and ICs
Transistors 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 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.
When you hear “IC”, think “chip”

19. 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 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.

20. Mainframe Computers. . .
Generally room-sized, with air conditioning, raised floors, etc
In the 1960s mainframe manufacturers were known as IBM and the 7 dwarfs (Burroughs, Control Data, General Electric, Honeywell, NCR, RCA, and UNIVAC)
Mainframes give lots of control – data is centralized
Mainframes were thought to be dying out in the early 90s but have turned out to be very useful
. . . 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.

21. 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.
Came around the same time as minicars and miniskirts
Mainframes were "corporate", minis were more rebellious
When I was in college, minis were booming –everyone wanted to work at DEC
Doesn't really exist as a category anymore

22. Doug Engelbart and the Mother of All Demos
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:
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
Instant messaging
This was in December of 1968!
Had been working on it since 1962, at SRI

23. Xerox PARC (Palo Alto Research Center)
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
Xerox Alto, 1973 – an early minicomputer, the first to use a GUI and desktop metaphor

24. The First Personal Computers
The Altair 8800 is commonly regarded as the beginning of the personal computer era, in 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.

25. Some Elderly PCs IBM Personal Computer, 1981
$3000 with 16K memory, 4.77 Mhz 8088 processor,
No hard drive
Apple II – 1977
$1298 with 4K RAM, $2638 with 48K RAM. 1 Mhz 6502 processor.
Compaq Portable, 1983 $ Mhz 8088 processor, 128K of RAM. Weighed 28 pounds – no battery, you had to plug it in.
Apple Macintosh, 1984
$2495 with 128K RAM, 7.83 Mhz processor
There were a million other companies in the business, too: Commodore, Radio Shack, Coleco, Atari, Amiga, Cromemco, Osborne, Sinclair, Epson, Timex, Franklin, Grid, Zenith, Kaypro, AT&T, Leading Edge, Amstrad, PCs Limited (started up in Michael Dell’s dorm room, later became Dell) and many more . . .
Apple Macintosh Portable: 1989 $7300 w/ hard drive. 16 Mhz processor, 1 Meg memory. Weighed 16 pounds, including battery

26. Moore's Law
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

27. 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