There are different ways to classify devices in general, and computers in particular.
Analog, Digital and Hybrid
An analog device is based on measurement or analogy.
e.g. speedometer, mercury thermometer, slide rule, differential analyzer
A digital device is based on counting or computing.
e.g. odometer, electronic digital computer
A hybrid device contains
(a) analog to digital converter
(b) digital to analog converter.
The early computers have names ending with -AC (meaning Automatic Computer).
EDSAC (built by Cambridge University)
EDVAC (designed by Eckert and Mauchly)
UNIVAC (built by Eckert & Mauchly’s company)
ILLIAC (built at University of Illinois)
There is no need now for terms such as Automatic.
Classification of Computers
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 (but not universally accepted)
Relative Size and Performance
Another way to classify is
Mainframe (standard) computer
- At the Computer History Museum (in Shoreline, Mountain View, California, USA), a visitor was showing his son the Cray-1 (Supercomputer of its time) which cost a whopping $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 how the Prime Movers and Early Adopters have contributed advances to Computer Science, Technology and Applications.