8.3.1 Exercises

8.3.1.1 Discussion

What device do you associate with the transistor?

How is the transistor used in a computer?

When and how were integrated circuits invented?

Where were the first integrated circuits used?

8.3.1.2 True or False

1. What does the speed at which a computer can perform calculations depend on?

2. The real transistor revolution was taking place in the field of the transistor radio.

3. In a computer the transistor is usually used as a switch rather than an amplifier.

4. The faster the transistors, the faster the computer.

5. Robert Noyce was the first to propose the idea of making the entire circuit directly on a silicon wafer.

6. The first integrated circuits (ICs) were very complicated and expensive.

8.3.1.3 Make presentations about

1) G. W. A. Dummer

2) Robert Noyce

3) William Shockley

4) Russell Ohl

5) John Bardeen and Walter Brattain

8.4 Text “Chips, Anyone?”

Integrated circuits (ICs) seem to be nearly everywhere—they’re in places such as your car’s engine and your car’s radio, telephones, iPods, and home thermostats; they’re in virtually all the technologies you interact with every day from ATMs to X-ray machines. And, of course, they’re in computers. Computers were one of the first places where ICs took hold, and they remain among the most recognizable technologies equipped with ICs.

Despite their increasingly small size, computers are extremely complicated technological systems. Inside a computer are a whole range of different chips that do everything from regulating power supplies and internal temperatures, to running sound and video systems, to controlling the spinning of hard drives and DVD burners. The most familiar chips are memory chips and microprocessors.

Memory chips store information, such as programs and data. The “main” memory chips that you see advertised are usually for storage of program data. These chips lose their data when power to the computer is turned off. Other memory chips store data permanently or until you change it, and there is some memory built into microprocessors and other types of chips.

The first Mosfet transistor, designed by M. M. Atalla, D. Kahng, and E. Labate in late 1959. Courtesy: Lucent.

Inside a typical main memory chip are tens of thousands or even millions of transistors—often in the form of a transistor called the metal oxide semiconductor or MOS, a device that was invented by Dawon Kahng and M. M. Attala. MOS transistors store information by switching on or off. In every computer, every piece of data is translated into a binary “code” of 0s and 1s. The letter “A” for example is translated into a binary number, 01000001. Then 01000001 is represented inside the chip as a set of transistors switched on (1) or off (0). A program like a web browser that deals with large amounts of text, displays pictures, accepts input from the user, and communicates with other computers needs millions of transistors to store all the coded information that passes through.

The microprocessor is another famous chip that resides in every computer. Unlike a memory chip, the microprocessor has many different functions, all carried out on one chip. Early computers had separate units (sometimes housed in different cabinets) for their mathematical and logic units, synchronization circuits or “clocks,” register units where various logic operations take place, buffers where data is held, circuits to accept data from the outside world, and so on. To make computers smaller, more energy efficient, and to move data around inside them more quickly, engineers began “integrating” those separate units onto one or more chips, then integrating those chips into a single “microprocessor,” or, in cases where engineers wanted to put a tiny computer into an industrial machine, a “microcontroller.” Gary Boone and others at Texas Instruments, and Federico Faggin, Stanley Mazor, Tedd Hoff and others at Intel Corporation developed the first microprocessors and microcontrollers.

Intel's Pentium 4 contains tens of millions of transistors. Courtesy: Intel

A chip is more than just a home for transistors. It also contains other elements needed to make a circuit, such as resistors, capacitors, and interconnecting conductors. But the usual way of comparing chips is to discuss the number of transistors on them. The first integrated circuits invented in 1958 had just a few transistors. The latest microprocessors have over 40 million.

Intel executive Gordon Moore was the first to observe this growth and the increase in numbers is often known as Moore’s Law.

To pack so many transistors and circuit elements onto one chip engineers have had to shrink the size of the parts. These smaller parts are, in fact, one of the major reasons for innovation in the integrated circuit field. The transistors that were about a centimeter wide in 1959 are now less than 200 billionths of a meter wide. That is so small that engineers are already predicting that the next generation of chips will have to be constructed in entirely new ways, perhaps assembled from individual molecules. This exciting new field is called “nanotechnology,” and it may open up entirely new directions for electronics in the 21st century.