Friday, 30 September 2011

Vaccum Tube

First Generation Computing (1946-1956)

Develop in the early 1950s. Involve massive computers using hundreds or thousands of vacuum tubes for their processing and memory circuitry.
The first computers used vacuum tubes for circuitry and magnetic drums for memory and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
In electronics, a vacuum tube, electron tube or thermionic valve reduce to simply 'tube' or ' valve' in everyday parlance, is a device that relies on the flow of electric current through a vacuum. Vacuum tubes may be used for rectification, amplification, switching, or similar processing or creation of electrical signals. 

Vacuum tubes rely on thermionic emission of electrons from a hot filament or cathode, that then travel through a vacuum toward the anode, which is held at a positive voltage relative to the cathode.
Vacuum tubes were critical to the development of electronic technology, which drove the expansion and commercialization of radio communication and broadcasting, television, radar,sound reproduction, largetelephone networks, analog and digital computers, and industrial process control. 

Although some of these applications had counterparts using earlier technologies, such as the spark gap transmitting computers, it was the invention of the triode vacuum tube and its capability of electronic amplification that made these technologies widespread and practical.

In most applications, vacuum tubes have been replaced by solid-state devices such as transistor and other semiconductor devices. Solid-state devices last much longer, and are smaller, more efficient, more reliable, and cheaper than equivalent vacuum tube devices.