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Punch Cards

The first data storage technology was punch cards, invented in the mid 1800ís. These were strips of thin cardboard with a grid of specific area. Each individual area represented a state, either they would have a hole or not and so represents a 1 or a 0. These cards were read by the computer by feeding them through a device which probed the areas to discover if they had a hole. Due to the nature of the cards they had a short life span, they would tear, bend and the holes would become worn. This method of storage had a very low storage to area ratio, for relatively simple programs hundreds of cards were required.

 

A Punch Card

In 1944 John Von Neumann had the idea of a "stored program." He suggested that instructions for computers could be stored in the computer's electronic memory as numbers and treated exactly the same as numerical data.

Vacuum tubes

This prompted scientists to research electronic storage possibilities. They came up with vacuum tubes also known as valves. These were electro-mechanical devices that electronically stored a state. They were used in the same way as punch cards but were not physically manipulated by the user, they were part of and controlled by the computer. Colossus one of the first computers used for code breaking during World War 2 used 1500 valves. The way computers worked changed because they now had access to their own memory that they could use to store and re-store data time after time, even in the same calculation. The storage to area ratio has actually decreased compared to the punch cards although there usefulness has greatly increased.

 

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Magnetic Tape

The Hard Disk  Drive

The Floppy Disk

The Compact Disk

The DVD

Magneto-Optical Storage

The future