Pascal's calculator Jacquard's loom Babbage's Difference Engine Hollerith's machine electromagnetic relay

Year Processor # Transistors
2000 Pentium 4 42,000,000 1999 Pentium III 1997 Pentium II 1993 Pentium 1989 80486 1,200,000 1985 80386 275,000 1982 80286 134,000 1978 8088 29,000 1974 8080 6,000 1972 8008 3,500 1971 4004 2,300
Intel Family of IC Chips
Jobs & Wozniak
Bill Gates
Deep Blue defeats Kasparov
While the previous generations of computers were defined by new technologies, the jump from generation 3 to generation 4 is largely based upon scale. By the mid 1970's,
advances in manufacturing technology led to the Very Large Scale Integration (VLSI) of hundreds of thousands and eventually millions of transistors on an IC chip. As an example of this, consider the table to the left that shows the number of transistors on chips in the Intel family. It is interesting to note that the first microprocessor, the 4004, had approximately the same number of switching devices (transistors) as the COLOSSUS, which utilized vacuum tubes in 1943. Throughout the sands, successive generations of IC chips added more and more transistors, providing more complex functionality in the same amount of space. It is astounding to note that the Pentium 4, which was released in 2000, has more than 42 million transistors, with individual transistors as small as 0.18 microns (0.00000000018 meters).
As the mass production of microprocessor chips became possible in the s with VLSI, the cost of computers dropped to the point where a single individual could afford one.
The first personal computer (PC, the MITS Altair 8800, was marketed in 1975 for under $500. In reality, the Altair was a computer kit that included all of the necessary electronic components, including the 8080 microprocessor that served as the central processing unit for the machine. The customer was responsible for wiring and soldering all of these components together to assemble the computer. Once assembled, the Altair had no keyboard, no monitor, and no permanent storage. The user entered instructions directly by flipping switches on the console, and viewed output as blinking lights. Despite these limitations, demand for the Altair was overwhelming.
While the company that sold the Altair, MITS, would fold within a few years, other small computer companies successfully charted the PC market in the late s. In 1976, Steven Jobs (1955-) and Stephen Wozniak (1950-) got their start selling computer kits similar to the Altair, which they called the
Apple. In 1977, they founded Apple Computer and began marketing the Apple II, the first pre-assembled personal computer with a keyboard, color monitor, sound, and graphics. By 1980, the annual sales of their Apple II personal computer had reached almost $120 million. Other companies, such as
Tandy, Amiga, and Commodore soon entered the market with personal computers of their own. IBM, which had been slow to enter the personal computer market, introduced the IBM PC in 1980, becoming an immediate force. Apple countered with the Macintosh in 1984, which introduced the now familiar graphical user interface of windows, icons, and a mouse.
As computers became the tools of more and more individuals, the software industry grew and adapted. Bill Gates (1955-) is credited with writing the first commercial software for personal computers, a BASIC interpreter for the Altair. In 1975, while a freshman at Harvard, he cofounded Microsoft along with Paul Allen (1955-) and helped to build that company into the software giant that it is today. Much of Microsoft's initial success was due to its marketing of the MS-DOS operating system for PCs, and applications programs such as word processors and spreadsheets. By the mid s, Microsoft Windows had become the dominant operating system for desktop computers, and Bill Gates, in his early shad become the richest person in the world.
The proliferation of programming languages continued in the sand beyond. In 1980, Alan Kay (1940-) developed Smalltalk, the first object-oriented language. Ada was developed for the
Department of Defense into be used for all government contracts. In 1985, Bjarne Stroustrup (1950-) developed Can object-oriented extension of CC+ and its offshoot Java
(developed in 1995 at Sun Microsystems) have become the dominant languages in software engineering today.

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