Classification of devices and computers

There are different ways to classify devices in general, and computers in particular.

Analog, Digital or Hybrid

An analog device is based on measurement or analogy.
Examples :

• Speedometer
• Mercury thermometer
• Slide rule
• Differential analyzer

A digital device is based on counting or computing.

Examples :

• Odometer
• Electronic digital computer
• Digital watch

A hybrid device contains

• Analog parts
• Digital parts

Converters

• Analog to digital converter
• Digital to analog converter.

Early Computers

Several early computers have names ending with -AC (meaning Automatic Computer).
Examples :

• EDSAC
  Built by M V Wilkes and team at Cambridge University
• EDVAC
  Designed by Eckert and Mauchly
• UNIVAC
  Built by Eckert & Mauchly’s company
• ILLIAC
  Built at University of Illinois
• SWAC and SEAC
  Computers for Bureau of Standards

There is no longer need for terms such as Automatic.

Computer Generations

One way to classify computers is by Generation.

• Zero Generation :
  Predates the electronic computers
• First Generation : uses Vacuum Tubes
• Second Generation
  Uses Transistors
• Third Generation
  Uses Integrated Circuits
• There are extensions for Fourth and Fifth Generations

Computer Types

Another way to classify is

• Micro computer
• Mini computer
• Mainframe
• Super computer

Other terms

• Portable computer
• Hand held computer
• Desk top computer
• Lap top computer
• Network computer
• Virtual machine

History

• At the Computer History Museum, a visitor was showing his son the Cray-1 (Supercomputer of its time) costing $10+ million.
  The son asked, “How fast is Cray-1?”
  The father replied, “Your smart phone and your PC at home are much faster than Cray-1.”
  
• We need to know the history and the context to appreciate the Prime Movers and Early Adopters for their contributions to Science and Technology.