Invention of Integrated Circuits

After the transistor was invented, scientists were attempting to figure out the smallest size for the transistor, since it had to be connected to wires and other electronics.Hence it was necessary to build a whole circuit (e.g.: the transistors, wires, etc) in a single unit. This integration of a large number of electronic components onto a single chip was a great achievement over the manual assembly of vacuum tubes and circuits using selected components.

The concept of Integrated Circuit (IC) was first published by a radar scientist, Geoffry W.A Dummer, working for the Royal Radar Establishment of the British Ministry of  Defense. But, his attempt to build the integrated circuit in 1956 was unsuccessful. This first IC was invented independently by two scientists: Jack Kilby of Texas Instruments, who filed a patent for a ‘solid circuit’ made of germanium and Robert Noyce of Fairchiled Semiconductor, who was awarded a patent for a complex’ unitary circuit’ made of silicon. In 1961 the first commercially available integrated circuits
came from the Fairchild Semiconductor Corporation. All computers consequently were made using chips instead of the individual transistors and their accompanying parts. Texas Instruments first used the chips in Air Force computers and in the Minuteman Missile in 1962. They later used the chips to produce the first electronic portable calculators. The original IC had only one transistor, three resistors and one capacitor and was the size of an adult's pinkie finger. Today an IC is smaller than a penny and can hold 125 million transistors. Mass production capability, reliability, and the ease of adding complexity were the main features of the IC. These features led to the development of standardized IC s, which replaced the electronic design done using vacuum tubes.

Level of Integrations

• SSI- Small Scale Integration 

Up to 100 electronic components per chip.These circuits used only a few transistors, which could be numbered in tens. These were used in early aerospace projects, such as the Minuteman missile and the Apollo program, which needed lightweight digital computers.

• MSI-Medium Scale Integration

From 100 to 3,000 electronic components per chip.These devices contained hundreds of transistors in a single chip. The more complex systems were built using small circuits with less assembly work through MSI.

• LSI-Large Scale Integration 

From 3,000 to 100,000 electronic components per chip.These devices contained thousands of transistors within a single chip. These were used to build computer main memories and pocket calculators.

• VLSI-Very Large Scale Integration

From 100,000 to 1,000,000 electronic components per chip.

This integration consists of millions of transistors in a single chip. This led to the development of the Microprocessor and the RAM chip.