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What is a computer?

• It is a Universal Information Manipulator

Universal

• Is a computer universal?
• How is it ‘universal’?

Information

• What is information?
  - numbers, words and instructions are examples of information
  - information is referred to as data

Manipulator

• How does the computer manipulate information?
• First, let’s talk about ways of storing information

Analog

• Webster’s New World dictionary defines analog as “a system of measurement in which a continuously varying values, as sound, temperature, etc. corresponds proportionally to another value, esp. a voltage”

Analog Devices

• Mercury thermometer
• Radio dial
• Clock with a second hand
• Slide rule

Analog Information

• Is mechanical
• Usually offers nearly infinite precision, but limited accuracy.

Digital

• Webster defines digital as “…a recording technique in which sounds or images are converted into groups of electronic bits and stored on a magnetic medium…”

Digital Devices

• Digital watches
• Digital thermometers

Digital Information

• Is information stored as a series of numbers
• Digital instruments are not as precise as analog counterparts, but are much more accurate

Computers – digital or analog?

• We think of computers as digital devices
• The digital nature of computers gives them their characteristics – limited precision but extreme accuracy

Information computers understand

• They understand numbers – more accurately 0’s and 1’s which is technically on or off in regards to fluctuations in electronic voltages

Binary storage

• Any mechanical device that exhibits yes/no behavior is referred to as a switch
• A computer is essentially a huge number of switches
• Voltages is an analog property, but forcing the circuitry to accept it as one of two values makes the computer a digital system

Binary Example