Page 22 - DCAP210_INTRODUCTION__TO_MICROPROCESSORS

Introduction to Microprocessors

Notes

History and Evolution of Microprocessors

he invention of the transistor in 1947 was a significant development in the world of
technology. It could perform the function of a large component used in a computer in
Tthe early years. Shockley, Brattain and Bardeen are credited with this invention and
were awarded the Nobel Prize for the same. Soon it was found that the function of this large
component was easily performed by a group of transistors arranged on a single platform.
This platform, known as the integrated chip (IC), turned out to be a very crucial achievement
and brought along a revolution in the use of computers. A person named Jack Kilby of Texas
Instruments was honoured with the Nobel Prize for the invention of IC, which laid the
foundation on which microprocessors were developed. At the same time, Robert Noyce of
Fairchild made a parallel development in IC technology for which he was awarded the patent.

ICs proved beyond doubt that complex functions could be integrated on a single chip with a
highly developed speed and storage capacity. Both Fairchild and Texas Instruments began
the manufacture of commercial ICs in 1961. Later, complex developments in the IC led to the
addition of more complex functions on a single chip. The stage was set for a single controlling
circuit for all the computer functions. Finally, Intel corporation’s Ted Hoff and Frederico
Fagin were credited with the design of the first microprocessor.
The work on this project began with an order from a Japanese calculator company Busicom to
Intel, for building some chips for it. Hoff felt that the design could integrate a number of
functions on a single chip making it feasible for providing the required functionality. This led
to the design of Intel 4004, the world’s first microprocessor. The next in line was the 8-bit 8008
microprocessor. It was developed by Intel in 1972 to perform complex functions in harmony
with the 4004.
This was the beginning of a new era in computer applications. The use of mainframes and
huge computers was scaled down to a much smaller device that was affordable to many.
Earlier, their use was limited to large organizations and universities. With the advent of
microprocessors, the use of computers trickled down to the common man. The next processor
in line was Intel’s 8080 with an 8-bit data bus and a 16-bit address bus. This was amongst the
most popular microprocessors of all time.
Very soon, the Motorola corporation developed its own 6800 in competition with the Intel’s
8080. Fagin left Intel and formed his own firm Zilog. It launched a new microprocessor Z80 in
1980 that was far superior to the previous two versions. Similarly, a break off from Motorola
prompted the design of 6502, a derivative of the 6800. Such attempts continued with some
modifications in the base structure.
The use of microprocessors was limited to task-based operations specifically required for
company projects such as the automobile sector. The concept of a ‘personal computer’ was
still a distant dream for the world and microprocessors were yet to come into personal use.
The 16-bit microprocessors started becoming a commercial sell-out in the 1980s with the first
popular one being the TMS9900 of Texas Instruments.

Intel developed the 8086 which still serves as the base model for all latest advancements in
the microprocessor family. It was largely a complete processor integrating all the required
features in it. 68000 by Motorola was one of the first microprocessors to develop the concept
of microcoding in its instruction set. They were further developed to 32 bit architectures.
Similarly, many players like Zilog, IBM and Apple were successful in getting their own
products in the market. However, Intel had a commanding position in the market right through
the microprocessor era.
Contd...

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