The late 1960s and early 1970s would bring advancements helping to aid the development of the personal computer. In 1968, Stanford Research Institute researcher Douglas C. Engelbart demonstrated a computer system consisting of a keyboard, keypad, a graphic user interface that used frames on a screen called "windows", a word processor, hypertext that allowed you to point-and-click on a word to produce another window with linked information, and a pointing device called a "mouse" that he had patented five years earlier after introducing it at a computer conference in San Francisco.

By then, Moore and Noyce's Intel had developed the first microprocessor memory chip, the 4004 in 1971 and, by 1972, had progressed to the eight-bit 8008 chip and, in 1974, to what was considered the first all-purpose microchip, the 8080. Enough interest had been stirred in technical research labs that people started thinking about home computers.

Featured on the cover of the January 1975 issue of Popular Electronics was the first personal computer, the Altair 8800. Using the Intel 8080 chip, the Altair was invented by an ex-Air Force officer from Georgia, Ed Roberts, and manufactured by his Albuquerque, N.M., company, MITS.

Hobbyists could buy these small personal computers in kit form, but had limited practical applications. They had to be programmed by toggle switches and had no monitors – just a lot of flashing lights. The idea sparked a fertile hobbyist culture in the San Francisco area, resulting in several ad hoc organizations, such as the Homebrew Computer Club in 1975.

It soon seemed that every hobbyist with a garage was building some sort of a personal computer. In 1977, two members of the Stanford Homebrew Computer Club, Steven Wozniak and Steven Jobs, formed a company called Apple Computer Inc., and introduced the first fully assembled personal computer for consumers, the Apple II. Within a year, they were unable to keep up with the overwhelming demand. A few years later, Paul Allen and Bill Gates set up shop in Albuquerque, N.M., to write computer programs.

By 1981, several companies such as Atari, Tandy and its TRS-80, Sinclair, Commodore and others had introduced small personal computers that were not very powerful. This changed when several entrepreneurs introduced sophisticated computers that ran software such as Basic programming language, MicroPro's WordStar (1979) and the SuperCalc spreadsheet program. Dr. Adam Osborne's Osborne 1, a 24-pound device with a five-inch screen, was the first "portable" personal computer when it hit stores in June 1981. Only 8,000 were sold that year, but sales jumped to 110,000 the following year. At one point, Osborne reported an order backlog of 25 months, but the company declared bankruptcy in September 1983. The Osborne 1 was followed by the Kaypro II transportable in late 1982, which experienced similar sales success.

But the real coming of age for the personal computer came between the introductions of the Osborne 1 and the Kaypro II: the unveiling of the IBM Personal Computer model 51510 in September 1981. The IBM PC used Intel's new 8088 chip, a wealth of off-the-shelf computing technology and, most importantly, an operating system called MS-DOS, provided by Gates and Allen, who had by this time founded a software company called Microsoft. IBM, the world's largest computer maker, quickly proved that there was a consumer market – at least for mainstream businesses – for the personal computer.

A host of companies such as DEC, NEC, Xerox, Epson, AT&T and HP – none of which previously believed that a mainstream consumer market existed – quickly jumped on the home PC bandwagon. These machines came to be known as "clones" since they essentially copied the technology included in the IBM PC, most of them running MS-DOS. In late 1983, IBM itself tried to capitalize on the market it had created by releasing its IBM PCjr, designed for the home market. The lack of innovation and its much derided "chicklet" keyboard doomed the product, however.

IBM followed up the PCjr. in 1984 with the Kaypro-like IBM transportable. A start-up company called Compaq made the first IBM-compatible portable in 1986.

Computers, however, required users to memorize a series of complex commands to operate their machines. In 1984, Apple unveiled the Lisa, which used a graphical user interface (GUI), developed originally at Xerox Corp.'s Palo Alto Research Center (PARC). Instead of a keyboard and arcane typed commands, Engelbart's mouse was used to move a cursor around the screen. Users placed the cursor at on-screen icons or selected items in pull-down menus that represented programs, functions and commands, and then clicked a button on the mouse to activate particular actions, a far more user-friendly way to control computer activities.

In January 1984, this so-called point-and-click technology came to the masses via the Apple Macintosh. A year later, Microsoft brought the GUI to IBM-compatible machines with the introduction of its Windows operating system. Both these operating systems introduced the concept of WYSIWYG – What You See Is What You Get – pronounced WHIZ-ee-wig. The idea was that what you saw on the screen is what your printer would produce.

After Windows and the Macintosh hit the market, the computer industry began the search for the "killer app" – a software application that would drive home computer sales. Word processing programs such as WordStar and spreadsheet programs such as Dan Bricklin's and Bob Frankston's VisiCalc (1981) slowly gave way to WordPerfect and Mitch Kapor's Lotus 1-2-3 (1983), and then to Microsoft versions, Word, also first introduced in 1983, and Excel, which now dominate the market. Another killer app, desktop publishing, was introduced with Aldus' PageMaker program in 1985, and allowed consumers to create their own sophisticated brochures, presentations and documents.

In 1990, Microsoft spent $10 million to promote Windows v3.0, considered the first version of Windows ready for prime time. In 1992, Windows was upgraded to v3.1, and Microsoft sold a million copies in the first 30 days. The next major Windows upgrade arrived three years later with Windows 95, which was backed with a $300 million ad campaign; within a year, the company had shipped 30 million copies.

The introduction of Windows 95 jumpstarted an operating system war when Apple accused Microsoft of stealing the "look and feel" of the Macintosh, ironic since Macintosh had itself stolen its look-and-feel from Xerox. The war of words and lawsuits, coupled with advances in modem technologies and simple-to-use software programs, energized the PC industry as more and consumers decided they wanted a personal computer at home. The use of the personal computer and digital networks allowed people to "telecommute" – work at home as efficiently as they worked in the office. A new type of small office/home office (SoHo) sprang into being, with tens of millions of workers abandoning their daily commute to work from home. Manufacturers of office equipment began designing phone systems, fax machines and photocopiers specifically for these smaller home-based operations.

Gordon Moore's famous 1965 "law" that chip performance would double every two years proved to be conservative. Early PCs running at 4 bits doubled to 8 with the IBM-PC, then to 16-bit with the IBM PC AT (Advanced Technology), and 32-bit with the Macintosh. Current personal computers run on 64-bit, 4 GHz-plus processors.

During the last 15 years, other computer technologies followed the precepts of Moore's law. Eight-inch floppy discs morphed into 5.25-inch floppy disks to 3.5-inch microfloppies in the late 1980s. But the need for more capacities have turned the venerable floppy disk into an anachronism and given rise to recordable CD disks and then to recordable DVD disks, and alternative high-capacity removable media technologies, such as the Iomega Zip and now to flash memory cards used in both PCs and portable devices such as MP3 players and digital cameras with capacities reaching 2 GB.

Hard drive capacity has expanded literally a million-fold. The first hard disk drive, the Ramac, was invented in the early 1950s by an IBM research team in San Jose, Calif., by a team led by Reynold B. Johnson, had 50 24-inch diameter double-sided aluminum magnetic disks, weighed a ton and stored a whopping five megabytes. Drives in early PCs stored only kilobytes, then megabytes, and now mini drives that are no larger than a quarter but can store more than a hundred gigabytes.

Printers moved from computerized typewriters to clunky dot-matrix printers requiring continuous feed sprocket-holed paper, to the introduction of the Hewlett-Packard ThinkJet, the first ink jet printer, and the HP LaserJet, the first consumer laser printer, both in 1984.

Monochrome screens slowly gave way to color screens in the mid-1980s, thanks in part to the introduction of the 256-color VGA monitor included with the IBM PS/2 line in 1987. The first flat-screen LCD panels began appearing in the late 1990s and are now the norm. In 2005, the first dual-core/dual-processing personal computers became available, allowing multiple applications to process data simultaneously with no loss of performance.