THE EVOLUTION OF COMPUTERS
Today’s personal computer, like the one shown in Figure 1-1, is a much more powerful Tcomputer than the PCs of just five years ago. Not to mention how different the PC is from computers way back in the early days of its development. Remember that the whole of the computer’s history is compacted into a little more than 50 years and the personal computer has only been around for a little over 20 years. In fact, the PC’s most spectacular development has probably been made in just the past five to ten years. It is also safe to say that the computer of today will be nothing compared to what we’ll have in five to ten more years. The one bit of good news in all of this is that the PC will most likely continue to have the same basic hardware components.
A BRIEF LOOK AT THE EVOLUTION OF COMPUTERS
Twenty-five years ago, it was virtually unthinkable that somebody would want to have a computer on their desk. Many of the “big” thinkers of the time could not even conceive of what anyone would possibly do with such a thing. It was a time of mainframes and minicomputers, which served the needs of corporations, companies, and departments. The idea that a single person could possibly have use for a computer all to themselves was just unthinkable.
Figure 1-1. Personal computers come in several styles
Mainframe Computers
Until the dawn of the personal computer in the early 1980s, computers were large, multiple cabinet affairs that required special room conditions and trained operators and program-mers. Mainframe computers, the larger of the computers (see Figure 1-2) can literally fill a room. These large computers, sold by IBM, Amdahl, Unisys, Hitachi, and others, are used to fulfill the computing needs of large companies and corporations and are also used in large telecommunications centers. They are very powerful with huge amounts of storage and processing capability. The drawbacks to the mainframe computer for use as a personal computer are its size, its immense amount of computing power, and its price, which can run into the millions of dollars.
Before the personal computer, each mainframe user worked at a terminal, which is a device that combines a display monitor with a keyboard and is attached directly to the mainframe computer by a dedicated cable. The terminal, so called because it terminates the connection line, allows the user to send large blocks of data—the contents of the entire display screen, actually—to the mainframe for processing, and the results are displayed on the terminal’s monitor. The early mainframe user did not have use of a mouse, and all data was entered as text. Graphical user interfaces (GUI) such as Microsoft Windows or X Windows were yet to come. Today’s mainframe user is more likely to be connected to the mainframe over a local network and to use a PC as a terminal device.
Figure 1-2. Mainframe computers provided computing for entire companies
Figure 1-3. Terminals, like the VT 520, are one way to connect to a mainframe. Photo courtesy of Boundless Technologies.
Minicomputers
The minicomputer was developed to serve the computing needs of smaller companies and the larger departments of corporations. The minicomputer, also known today as a mid range computer, has essentially the same functionality of the larger main-frame computer but on a smaller scale—and not much smaller, at that. The minicomputer was developed largely to open new markets for computers after most of the larger com-panies had purchased mainframes. The mainframe was scaled into a smaller package with most of its functions remaining and a little less storage and processing power, sold at a reduced price. There are computing devices today, made by Hewlett Packard, Compaq, and others, that are manufactured under the name minicomputer that are in fact midlevel computers that are more powerful than personal computers and less pow-erful than a mainframe. Because of advances in technology, today’s minicomputer can
Figure 1-4. Minicomputers were as powerful as mainframes, only smaller
fulfill the entire computing needs of a small- to medium-sized company as well as serve as a very powerful communications server. Minicomputers are much too big, in terms of processing power and size, not to mention price, to be used as a personal computer.
Other Computers
You may have heard of a couple of other computer classifications: the supercomputer and the embedded computer. A supercomputer, like the one pictured in Figure 1-5, is an extremely powerful computer used mostly in research and space, military, and govern-mental applications. A supercomputer, which can cost tens of millions of dollars, contains the equivalent of thousands of personal computers that share in the processing load to solve very large and complex problems in hours or days instead of weeks, months, or years. A supercomputer is the largest and most powerful computer, sometimes equaling the power of several mainframes combined. For example, the Massachusetts Institute of Technology (MIT) is using a supercomputer to calculate the value of the mathematics.
Figure 1-5. A supercomputer is the most powerful of the computer family
Value of pi to over a million decimal places, so far. Although it is the stuff dreams are made of, a supercomputer is way beyond consideration as a personal computer.
It seems as if virtually all electronic devices have a computer built into them in some way. These very small and single purpose processors are classified as embedded computers. An embedded computer is built into another device to control, monitor, or manage some activity for the device. The controls of a microwave oven, the carburetion on your car, the function of your electronic alarm clock, even your wristwatch most likely, all have at least one, and probably more, embedded computers. While it is true that a personal computer also has an embedded computer in its microprocessor (more on this later), the PC’s processor is a multifunction device capable of controlling more than a single process or activity.
The Evolution of Personal Computers
There is some argument about what was actually the very first personal computer. Some say it was the MITS Altair 8800 (see Figure 1-6), and others claim it was the Apple. It may depend on the definition you use for just what a personal computer is, or was.
The Altair 8800 was a kit computer that fast became the favorite of hobbyists looking to get a computer all their own. Ed Roberts and his company, MITS (Model Instrumenta-tion Telemetry Systems), developed this early personal computer kit, which was named the Altair by his daughter after a planetary destination on the TV show Star Trek.
The soft-ware for the MITS was a BASIC programming language written by a fledgling company called Microsoft. However, like nearly all early personal computers, the Altair 8800 did not have off-the-shelf application software, and users had to write their software them-selves using the BASIC language interpreter. While this was a challenge, to those kindred spirits looking to get in on the computing craze, it wasn’t a problem.
In 1978, after seeing a demonstration of the Altair 8800, two young computer enthusi-asts, Steve Jobs and Steve Wozniak, set out to build their own computer and developed a computer they named the Apple I. Like its predecessors, the Apple I established a follow-ing that encouraged its young developers to continue. The Apple II soon followed (see Figure 1-7), bolstered by what may have been the first killer application, an early spread-sheet program called VisiCalc, and became a commercial success.
It wasn’t long before nearly every mainframe and minicomputer manufacturer leaped into the personal computer market. IBM, Digital Equipment, and others soon had their own PCs in the marketplace. The IBM PC and its extended technology (XT) and advanced tech-nology (AT) versions soon became the standard for computers using Intel microprocessors,
Figure 1-6. The Altair MITS is thought to have been the first personal computer
Figure 1-7. The Apple computer was the first commercially successful personal computer
while Apple Computer continued to carve its own niche. The IBM PC AT (see Figure 1-8) and the Apple Macintosh (see Figure 1-9) represent commercially successful PCs that largely defined the personal computer in terms of its size, shape, and functions—a standard that has continued until today. This is the point at which we will begin looking at the technology of the PC and its hardware.
The PC over the Years
Figure 1-8. The IBM PC AT established the standard for Intel-based personal computers
Figure 1-9. The Apple Macintosh established a strong niche market early on .
Year Event
1961 Fairchild Semiconductor releases the first commercially available
integrated circuit.
1963 Douglas Engelbart patents the mouse pointing device.
1970 Intel introduces the 4004 microprocessor.
1971 IBM introduces the floppy disk.
1974 Intel releases the 8080 microprocessor.
1975 MITS Altair 8800 sells in kit form for $375.
1976 Steve Wozniak and Steve Jobs build Apple I.
1977 Microsoft Corporation formed by partners Bill Gates and Paul Allen.
Apple Computer produces Apple II.
1978 Intel produces the 8086 microprocessor.
1979 VisiCalc, the first killer application, is released. Intel produces the
8088 microprocessor.
1980 Apple III computer is introduced.
The Radio Shack TRS-80 is introduced.
1981 IBM 5150 PC released featuring PC DOS (MS-DOS) 1.0.
1982 Commodore 64 computer is introduced.
Intel produces the 80286 microprocessor.
The Compaq Portable PC is introduced.
1983 Lotus 1-2-3 application is released.
IBM PC XT is introduced.
MS-DOS 2.0 is released.
1984 Hewlett Packard releases the LaserJet printer.
Phoenix ROM BIOS is released.
1985 Intel releases the 80386DX.
Microsoft Windows 1.0 is released.
PC CD-ROM drives are made available.
1986 The first 80386 PC is produced.
1987 Apple Macintosh computer is introduced.
IBM introduces PS/2 computers featuring OS/2 and VGA graphics.
1988 Intel releases the 80386SX microprocessor.
Steve Jobs introduces the NeXT computer.
1989 Intel announces the 486 microprocessor.
1990 Microsoft Windows 3.0 is released.
1991 AMD releases its clone of the 386 microprocessor.
1992 Intel releases the 486DX2 microprocessor.
Windows 3.1 is released.
1993 The Intel Pentium microprocessor is announced.
1994 Netscape Navigation browser is released.
Iomega introduces the Zip drive.
1995 Pentium Pro microprocessor is introduced.
1998 Pentium II microprocessor is released.
As you can see, many separate events, all of them loosely related, were instrumental in the development of the personal computer as it exists today. The general structure of the PC has changed very little since its beginnings in the late 1970s. However, its speed, capacities, and power have increased nearly exponentially.
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