Metaphor: The Analytical Engine

€ Mechanical calculators have been with us for a long time.

Abacus (several thousand years old)

Pascal's calculator (1642)

Babbage's Difference Engine (1822)

€ Babbage's Analytical Engine could be programmed . . . .

Just like computers today.

Origins

€ New ideas have moved us from center stage:
- Copernicus (1543)

- Geologists in the eighteenth and nineteenth
centuries

- Darwin

€ The Industrial Revolution: the embodiment of skills in machines.

€ The Jacquard loom (1799) mechanized expertise.

€ The Difference Engine: A sequence of calculations was embodied in the design.

€ The Analytical Engine (1833): using punched cards as input, it would
perform any sequence of calculations

"The weaver of algebra"

Handling the Information Explosion

€ Herman Hollerith's tabulating machines for the 1890 census:
electromechanical devices.

€ Telegraph: electronic representation of information.

A relay from an electromechanical device

A vacuum tube from an electronic device

Early Computers

ABC ( Atanasoff-Berry-Computer): designed to
solve systems of simultaneous linear equations.

Z1, Z2, Z3, and Z4: electromechanical general-
purpose computers.

Military Computers

Mark I computer: used for weather prediction.

Colossus: used to decode German messages.

ENIAC: produced ballistic firing tables. A
stored-program computer.

Generations

€ First generation: vacuum tubes

- 1950s
- Thousands of tubes required enormous power
- Large
- Expensive for limited computational power

€ Second generation: transistors

- Late 1950s and early 1960s
- Transistors require much less power than tubes
- Tubes blow out. Transistors don't
- Transistors can be made very small
- Transistors are faster than tubes

€ Third generation: integrated circuits (IC)

- Late 1960s and early 1970s
- Thousands of transistors on a single silicon chip
- Faster, smaller, cheaper, more powerful
- Microprocessors‹entire computers on a single chip
- Embedded computers

€ Fourth generation: large-scale integrated circuits (LSI)

- Late 1970s to today
- More complex circuits
- Computer as consumer item
- Still faster, smaller, cheaper, more powerful

€ If automotive technology had developed at the
same rate as computer technology, a new car today:

Would have an engine less than an inch across

Would get 120,000 miles per gallon

Would have a top speed of 240,000 miles per hour

Would cost four dollars