The Computing Revolution
Technology changes rapidly. The computer was introduced in the late 1930s. The Boston Museum of Science has highlighted the computing revolution in the follow- ing website: www.mos.org/exhibits/ComputingRevolution. Please refer to this URL for a detailed discussion as well as pictorial examples of the computer generations discussion which follows.
The First Generation of Computers
Developed in 1944, the Mark I, made up of mechanical switches that opened and closed by electrical current, was 51 feet long, 8 feet high, and contained 1 million com- ponents and over 500 miles of electric wire. At approximately the same time, Grace Hopper and others were beginning to develop the computer languages that were necessary to program these new electronic computers. The next major development in computer technology culminated in the Electronic Numerical Integrator and Com- puter (ENIAC). Designed by John W. Mauchly and J. Prespert Eckert, Jr., ENIAC was intended to be used by the military. It was programmed by means of switches and connections. ENIAC was more than 1,00d0 times faster than the Mark I, performing 5,000 calculations per second. Weighing 60,000 pounds and containing nearly 20,000 vacuum tubes, ENIAC required tremendous amounts of electricity and gave off large amounts of heat (see Figure 1.1).
The most significant feature of ENIAC was that it introduced vacuum-tube technology, and no longer were calculations and operations performed by moving mechanical parts. This gesture allowed for greatly increased speed of performance
The first generation of computers, which thrived from 1951 until 1959, was char- acterized by vacuum-tube technology. Although they were amazing devices in their time, they were large, expensive to operate, and required almost constant mainte- nance to function properly. The next generation of computers attempted to resolve some of these problems.
The Second Generation of Computers
The second generation of computers extended from 1959 until 1964 and was char- acterized by transistor technology. The transistor was developed in 1947 by John Bardeen, Walter H. Brattain, and William B. Shockley at Bell Laboratories in New Jersey. Bardeen, Brattain, and Shockley studied substances that permitted a lim- ited flow of electricity through semiconductors. Transistors that used semicon- ductor material could perform the work of vacuum tubes and took up muchless space. (see Figure 1.2)
An electronic panel containing transistors. Invention of the transistor made possible a decrease in the size and an increase in the power of computers.An electronic panel containing transistors. Invention of the transistor made possible a decrease in the size and an increase in the power of computers. An electronic panel containing transistors. Invention of the transistor made possible a decrease in the size and an increase in the power of computers.
Because transistors were smaller, the distance between operating parts was re- duced, and speed of performance was increased significantly. Transistors were also much cooler than vacuum tubes, reducing the need for expensive air conditioning in areas where computers were housed (see Figure 1.2).
Transistors did present several problems, though. They were relatively expensive because each transistor and its related parts had to be inserted individually into holes in a plastic board. In addition, wires were fastened by floating the transistor board in a pool of molten solder. The number of parts required for even the simplest transistors was staggering. The next generation of computers helped to alleviate some of these problems.
The Third Generation of Computers
The development of integrated circuits in 1963 spawned the third generation of computers, lasting from 1964 until 1975. The production process begins when tubes of silicon are sliced into wafer-thin disks that are chemically pure and cannot hold electrical charge. A preconceived design is etched onto the sur- face of the wafer with the use of light rays and the wafer is placed in an acid bath to eliminate all unex- posed areas. To enable the wafer to carry an electrical impulse, slight traces of impurities must be added in a specified pattern. Finally, a fine diamond saw slices through the wafer and divides it into dozens of blocks, like postage stamps in a large sheet. Each tiny piece is now a chip, which is encased and connected to the outside of the case with gold wires (see Figure 1.3).
Third-generation computers were designed as general-purpose computers, representing a giant leap forward in the data-processing field. Not only were speed and reliability enhanced, but power consumption was decreased markedly. Computers became smaller and less expensive, putting computer power into the hands of a greater number of users than ever before.
The Fourth Generation of Computers
As engineers learned how to manufacture chips more easily, they conceived the idea of grouping an assortment of functions on a single chip, creating a microelectronic “system” capable of performing various tasks required for a single job. This technology became known as large-scale integration (LSI). Thus, the fourth generation of computers was born in the mid-1970s.
LSI has many applications other than large-scale computers, such as the pocket calculator and the digital watch. Still another innovation of LSI technology was the computer-on-a-chip. Its manufacturers compress nearly all the subsystems of a computer into 1/20 square inch. This led to Intel developing in 1971 the world’s first microprocessor. The 4004 was made up of 2,250 transistors, while today the Pentium 4 processor has over 42 million transistors (see Figures 1.4, 1.5, and 1.6). LSI technology is responsible for the popularity of the computer, as prices have continued to decline and computers are easier to maintain. (See Table 1.1 for a summary of this decline in computer costs.)
Future Generations of Computers
A hint of tomorrow’s computer capability can be found in very large-scale integrated (VLSI) cir- cuitry, which further increased the speed at which computers were able to function.
Multiprocessing, the simultaneous running of several programs by one computer, is being developed further in fifth-generation comput- ers. Today, the personal computer has become an important interactive tool for teaching and learning. Multimedia peripherals, CD-ROM (compact disc read-only memory), CD-RW (compact disc rewritable), and DVD-RW (digital versatile disc) can be interfaced with the personal computer and the World Wide Web, which greatly expanded its utilization.
TABLE 1.1 Decreasing Cost of Computer Operations
|Generations||Technology||Cost per 100,000 Computations|
|Fourth||LSI||Less than 0.01|
Personal computers with their multimedia capabilities are continually being integrated into the classroom curriculum. Using personal computers and the World Wide Web, educators are creating new learning environments. Within these environments, teachers become facilitators and students become constructors of knowledge. Together, teachers and students become knowledge navigators, a term coined by John Sculley, past CEO of Apple Computers.