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Microprocessors

 

The microprocessor itself is actually just a type of integrated circuit. In November 1971, Intel introduced the world's first commercial microprocessor, the 4004, invented by three Intel engineers. Primitive by today's standards, it contained a mere 2300 transistors and performed about 60,000 calculations in a second. Twenty-five years later, the microprocessor is the most complex mass-produced product ever, with more than 5.5 million transistors, all either acting as amplifiers, oscillators or switches. In addition to the transistors, other components, such as resistors, diodes, capacitors and wires are packed on to the CPU chip.

The microprocessor's introduction revolutionised the computer industry in the second half of the 20th century. Previously, computers had been huge machines, filling multiple rooms. There were other problems too: the impractical vacuum tubes in use in computers at the time led to constant reliability and heating problems. The invention of the transistor and subsequent invention of the integrated circuit enabled scientists to invent the microprocessor, which was to transform computers from massive expensive contraptions, to the desktop, laptop and palmtop PC's so useful in our lives today.

The transistor used most commonly in the microelectronics industry is called a metal-oxide semiconductor field-effect transistor (MOSFET).


Construction of Microprocessors

The Microprocessor is made using techniques which are very similar to those used in manufacturing other integrated circuits. However, because of their extremely complex structure, their manufacture requires extremely precise techniques. In order to make them more economical, microprocessors are mass-produced. Several hundred dies, or circuit patterns, are created on the surface of a silicon wafer simultaneously. Microprocessors are constructed by a process of deposition and removal of conducting, insulating, and semiconducting materials one thin layer at a time until, after hundreds of separate steps, a complex sandwich is constructed that contains all the interconnected circuitry of the microprocessor. Only the outer surface of the silicon, a layer about one-tenth the thickness of a human hair, is used for the electronic circuit. The processing steps include substrate creation, oxidation, lithography, etching, ion implantation, and film deposition.


History

As mentioned earlier, the first microprocessor was invented in 1971 by three Intel engineers. The Intel 4004, which was originally developed for use in calculators, contained about 2300 transistors on a 4-bit microprocessor that could perform only 6000 operations per second. The first 8-bit microprocessor was the Intel 8008, developed in 1972 to run computer terminals. The Intel 8008 contained 3300 transistors. The first truly general-purpose microprocessor, developed in 1974, was the 8-bit Intel 8080, which contained 4500 transistors and could execute 200,000 instructions per second. Modern microprocessors have much greater capacity and speed. Current processors are mostly 32-bit, with 64-bit versions currently being developed. These current microprocessors include the Intel Pentium III and the AMD Athlon, containing sveral millions transistors. By the year 2010, microprocessors are expected to contain as many as 800 million transistors.


Introduction to Semiconductors
This topic will introduce you to the concept of semiconductors which are an integral part in the making of transistors.

Semiconductor Diodes
The prerequisite information on diodes that later went on to give the birth to the semiconductor triode - otherwise known as the transistor.

Semiconductor Triodes
Another name for the transistor...

Types of Transistors
Learn the various types of transistors and how they function.

Amplification
This is the basic function of the transistor - and the most important one!

Switches
Next to amplification, this is the most common function of transistors.

Comparisions
Learn the analogies and the differences between the older vacuum tube triodes and the slicker new transistors.

Integrated circuits
These are the most common applications of transistors and go a long way in building powerful microprocessors and appliances. Learn the role that transistors play in them.

Microprocessors
These are the real brains of most electronic appliances around us. Explore the vital role played by their grey cells - transistors.

Appliances affected
Realize the full potential of these transistors through the various appliances they revolutionized, right from your digital watch to this PC.

The pre- and post-transistor world
To understand the impact of the transistor in its entirety, perceive what the world was before, and what it is after 1947 - when the transistor was invented.

Future trends
Revolution is an unending process. Take a sneak preview of where the transistors of the future are headed.

History
Understanding of the transistor becomes clearer when learnt in context of its evolutionary journey. Here, we have presented the most important landmarks in its journey of almost a century.

Build the transistor
Theoretical knowledge weighs nothing unless put to practice. Learn how the different types of transistors are built and build some on your own!

Learn the circuits
Learn how the actual amplification and switching takes place by building your own circuits and watching the current flow.

Drive-the-circuit
If you have the necessary stuff in your head, come and test drive a BJT amplification circuit! But watch out for the speed bumps along the way!

Message Boards
Leave your own messages and discuss different topics with fellow surfers.

Ask-a-mentor
Nobody's perfect...we are no exception. But we certainly try to be perfect. If you have any questions about transistors that were not answered in this site, ask our mentors...

Learners' Center
Discuss your views with other users of this site. There are topics like Message Board, Translate-the-site and Simplify-the-site!

Quizzes
These are quizzes to rack your grey cells. If you think that you have surfed this site entirely, solve these! They include Multiple choice questions and Scrambled words to solve!

Learn in a Flash
These are our step-by-step interactive tutorials to brief you up about the world of transistors.

Advanced Section
This section includes an in-detail explanation on this topic. For you to understand the Advanced section, you should have a basic knowledge of the fundamentals involved. To learn more, please select the section called Prerequisites from the bottom of the page.

Basic Section
Return to the Basic section.

Prerequisites
This section is meant to explain the fundamentals involved in the knowledgae of transistors!
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Citations and Copyrights
A list of our sources and also copyright notices of material used in making this site.
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