Personal computer

2008/9 Schools Wikipedia Selection. Related subjects: Computing hardware and infrastructure

A personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals, intended to be operated directly by an end user, with no intervening computer operator.

A personal computer may be a home computer, or may be found in an office, often connected to a local area network. The distinguishing characteristics are that the computer is used only (or mostly) by one person at a time, in a very interactive fashion. This is opposite to the batch processing or time-sharing models which allowed large expensive systems to be used by many people, usually at the same time, or large data processing systems which required a full-time staff to operate efficiently.

The capabilities of a personal computer have changed greatly since the introduction of electronic computers. By the early 1970s, people in academic or research institutions had the opportunity for single-person use of a computer system in interactive mode for extended durations, although these systems would still have been too expensive to be owned by a single person. The introduction of the microprocessor, a single chip with all the circuitry that formerly occupied large cabinets, lead to the proliferation of personal computers after about 1975. Early personal computers generally called microcomputers, sold often in kit form and in limited volumes, and were of interest mostly to hobbyists and technicians. By the late 1970s, mass-market pre-assembled computers allowed a wider range of people to use computers, focusing more on software applications and less on development of the processor hardware. Throughout the 1970s and 1980s, home computers were developed for household use, offering personal productivity, programming and games. Somewhat larger and more expensive systems (although still low-cost compared with minicomputers and mainframes) were aimed for office and small business use. Workstations are characterized by high-performance processors and graphics displays, with large local disk storage, networking capability, and running under a multitasking operating system. Workstations are still used for tasks such as computer-aided design, drafting and modelling, computation-intensive scientific and engineering calculations, image processing, architectural modelling, and computer graphics for animation and motion picture visual effects.

Eventually the market segments lost any technical distinction; business computers acquired colour graphics capacity and sound, and home computers and game systems used the same processors and operating systems as office-bound computers. Mass-market computers had graphics and memory comparable to dedicated workstations of a few years before. Even local area networking, originally a way to allow business computers to share expensive mass storage and peripherals, became a standard feature of a home computer.

Today a personal computer may be a desktop computer, a laptop computer, or a tablet computer. The most common operating systems are Microsoft Windows, Mac OS and Linux, while the most common microprocessors are the x86 and PowerPC CPUs. Software applications for personal computers include word processing, spreadsheets, games, and a myriad of personal productivity and special-purpose software. Modern personal computers often have high-speed or dial-up connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. While early personal computer owners usually had to write their own programs to do anything useful with the machines, today's users have access to a wide range of commercial and free software which is easily installed. The coming convergence between larger devices and the Personal Digital Assistants (PDAs), mobile phone and wearable computer markets which have similar functions, operating systems and even the same components, will decide if personal computer will refer to these devices..

Etymology

One early use of the term "personal computer" appeared in a November 3, 1962, New York Times article reporting John W. Mauchly's vision of future computing as detailed at a recent meeting of the American Institute of Industrial Engineers. Mauchly stated, "There is no reason to suppose the average boy or girl cannot be master of a personal computer."

Six years later a manufacturer took a risk at referring to their product this way when Hewlett Packard advertised their "Powerful Computing Genie" as "The New Hewlett Packard 9100A personal computer". This advertisement was too extreme for the target audience and replaced with a much drier ad for the HP 9100A programmable calculator.

During the next seven years the phrase had gained usage so when Byte magazine, published its first edition it referred to its readers as being in the "personal computing field", while Creative Computing defined the personal computer as a "non-(time)shared system containing sufficient processing power and storage capabilities to satisfy the needs of an individual user." Two years later when the 1977 Trinity of preassembled small computers hit the markets, the Apple II and the PET 2001 were advertised as personal computers, while the TRS-80 was a microcomputer used for household tasks including "personal financial management". By 1979 over half a million microcomputers were sold and the youth of the day had a new concept of the personal computer.

On January 3 1983, the Personal Computer was the first non-human to be announced as Person of the Year by Time Magazine, in 1982.

The initialism PC may refer generically to a personal computer, or may be intended to refer to one of the original IBM PC compatible computers, or may refer to a Microsoft Windows computer currently available.

History

Mainframes and large minicomputers

Before the introduction of the microprocessor in the early 1970s, computers were generally large, costly systems owned by large corporations, universities, government agencies, and similar-sized institutions. End users often did not directly interact with the machine, but instead would prepare tasks for the computer on off-line equipment, such as card punches. A number of assignments for the computer would be gathered up and processed in batch mode. After the job had completed, users could collect the results. In some cases it could take hours or days between submitting a job to the computing centre and receiving the output.

A more interactive form of computer use developed commercially by the middle 1960s. In a time-sharing system, multiple computer terminals let many people share the use of one mainframe computer processor. This was common in business applications and in science and engineering.

A different model of computer use was foreshadowed by the way in which early, pre-commercial, experimental computers were used, where one user had exclusive use of a processor. Some of the first computers that might be called "personal" were early minicomputers such as the LINC and PDP-8, and later on VAX and larger minicomputers from Digital Equipment Corporation (DEC), Data General, Prime Computer, and others. By today's standards they were very large (about the size of a refrigerator) and cost prohibitive (typically tens of thousands of US dollars), and thus were rarely purchased by an individual. However, they were much smaller, less expensive, and generally simpler to operate than many of the mainframe computers of the time. Therefore, they were accessible for individual laboratories and research projects. Minicomputers largely freed these organizations from the batch processing and bureaucracy of a commercial or university computing centre.

In addition, minicomputers were relatively interactive and soon had their own operating systems. The minicomputer Xerox Alto (1973) was a landmark step in the development of personal computers, because of its graphical user interface, bit-mapped high resolution screen, large internal and external memory storage, mouse, and special software.

Microprocessor and cost reduction

The minicomputer ancestors of the modern personal computer used early integrated circuit (microchip) technology, which reduced size and cost, but they contained no microprocessor. This meant that they were still large and difficult to manufacture just like their mainframe predecessors. After the "computer-on-a-chip" was commercialized, the cost to manufacture a computer system dropped dramatically. The arithmetic, logic, and control functions that previously occupied several costly circuit boards were now available in one integrated circuit, making it possible to produce them in high volume. Concurrently, advances in the development of solid state memory eliminated the bulky, costly, and power-hungry magnetic core memory used in prior generations of computers.

There were a few researchers at places such as SRI and Xerox PARC who were working on computers that a single person could use and could be connected by fast, versatile networks: not home computers, but personal ones.

Kenbak-1

The Kenbak-1 is considered by the Computer History Museum to be the world's first ever personal computer. Only around 40 machines were ever built and sold. With only 256 bytes of memory, an 8-bit word size, and input and output restricted to lights and switches, the Kenbak-1 was most useful for learning the principles of programming but not capable of running application programs.

Datapoint 2200

A programmable terminal called the Datapoint 2200 is the earliest known device that bears any significant resemblance to the modern personal computer, with a screen, keyboard, and program storage. It was made by CTC (now known as Datapoint) in 1970 and was a complete system in a small case bearing the approximate footprint of an IBM Selectric typewriter. The system's CPU was constructed from a variety of discrete components, although the company had commissioned Intel to develop a single-chip processing unit; there was a falling out between CTC and Intel, and the chip Intel had developed wasn't used. Intel soon released a modified version of that chip as the Intel 8008, the world's first 8-bit microprocessor. The needs and requirements of the Datapoint 2200 therefore determined the nature of the 8008, upon which all successive processors used in IBM-compatible PCs were based. Additionally, the design of the Datapoint 2200's multi-chip CPU and the final design of the Intel 8008 were so similar that the two are largely software-compatible; therefore, the Datapoint 2200, from a practical perspective, can be regarded as if it were indeed powered by an 8008, which makes it a strong candidate for the title of "first microcomputer" as well

Altair 8800 and IMSAI 8080

Development of the single-chip microprocessor was an enormous catalyst to the popularization of cheap, easy to use, and truly personal computers. The Altair 8800, introduced in a Popular Electronics magazine article in the January 1975 issue, at the time set a new low price point for a computer, bringing computer ownership to an admittedly select market in the 1970s. This was followed by the IMSAI 8080 computer, with similar abilities and limitations. The Altair and IMSAI were essentially scaled-down minicomputers and were incomplete: to connect a keyboard or screen to them required heavy, expensive "peripherals". These machines both featured a front panel with switches and lights, which communicated with the operator in binary. To program the machine, one didn't simply power up: one first had to key in the bootstrap loader program in binary, then read in a paper tape containing a BASIC interpreter, using a paper-tape reader. Keying the loader required setting a bank of eight switches up or down and pressing the "load" button, once for each byte of the program, which was typically hundreds of bytes long. This was before one could begin to do any computing.

The MITS Altair, the first commercially successful microprocessor kit, was featured on the cover of Popular Electronics magazine in January 1975. It was the world's first mass-produced personal computer kit, as well as the first computer to use an Intel 8080 processor. It was a commercial success with 10,000 Altairs being shipped. The Altair also inspired the software development efforts of Paul Allen and his high school friend Bill Gates who developed a BASIC interpreter for the Altair, and then formed Microsoft.

The MITS Altair 8800 effectively created a new industry of microcomputers and computer kits, with many others following, such as a wave of small business computers in the late 1970s based on the Intel 8080, Zilog Z80 and Intel 8085 microprocessor chips. Most ran the CP/M-80 operating system developed by Gary Kildall at Digital Research. CP/M-80 was the first popular microcomputer operating system to be used by many different hardware vendors, and many software packages were written for it, such as WordStar and dBase II.

Many hobbyists during the mid 1970s designed their own systems, with various degrees of success, and sometimes banded together to ease the job. Out of these house meetings the Homebrew Computer Club developed, where hobbyists met to talk about what they had done, exchange schematics and software, and demonstrate their systems. Many people built or assembled their own computers as per published designs. For example, many thousands of people built the Galaksija home computer later in the early 80s.

It was arguably the Altair computer that spawned the development of Apple, as well as Microsoft which produced and sold the Altair BASIC programming language interpreter, Microsoft's first product. The second generation of microcomputers — those that appeared in the late 1970s, sparked by the unexpected demand for the kit computers at the electronic hobbyist clubs, were usually known as home computers. For business use these systems were less capable and in some ways less versatile than the large business computers of the day. They were designed for fun and educational purposes, not so much for practical use. And although you could use some simple office/productivity applications on them, they were generally used by computer enthusiasts for learning to program and for running computer games, for which the personal computers of the period were less suitable and much too expensive. For the more technical hobbyists home computers were also used for electronics interfacing, such as controlling model railroads, and other general hobbyist pursuits.

Heathkit and Zenith

In 1978, the Heath company introduced the Heathkit H-8 computer. The early computers like the Altair had been sold as kits, but Heath had real experience in producing kit electronic equipment and the Heath name carried confidence with it. The H-8 was successful, as were the H-19 and H-29 terminals, and the H-89 one piece terminal/computer (The H-8 and H-89 ran their custom operating system, HDOS). The H-11, a low-end DEC PDP-11 16-bit computer, was less successful probably because it was substantially more expensive than the 8-bit computer line. (A generation earlier (1956),Heathkit sold a kit for a vacuum tube analog computer which could also be considered a form of personal computer.

Zenith Radio Company bought Heath Company from Schlumberger in 1979, renaming the computer division Zenith Data Systems (ZDS). Zenith was in the vanguard of companies to start selling personal computers to small businesses. The H-89 kit was re-branded as the Z89/Z90, an assembled all in one system with a monitor and a floppy disk drive. They had agreements with Peachtree software to sell a customized "turn-key" version of their accounting, CPA and real estate management software. Shortly after the release of the Z90, they released a 5 MB hard disk unit and double density external floppy disk drives. While the H11 was popular with hard-core hobbyists, Heath engineers realized that DEC design would not be able to get Heath up the road to more powerful systems. Heath/Zenith then designed a dual Intel 8085/8088 based system dubbed the H-100 (or Z-100, in preassembled form). The machine featured very advanced (for the day) bit mapped video that allowed up to 640 x 512 pixels of 8 colour graphics. The 100 was interesting in that it could run either the CP/M operating system, or their OEM version of MS-DOS (Z-DOS).

Apple II, TRS-80 and Commodore PET

1977 saw a race to be the first commercially successful pre-built microcomputer. The competitors were the Apple Computer Apple II, Commodore International PET 2001 and the Tandy TRS-80 Model I. The MOS Technology 6502 series microprocessor lead to a reduction in the expense of creating computing systems. The Commodore PET, the TRS 80, and the Apple II, also known as the 1977 Trinity by Byte magazine, are often cited as the first personal computers. Specifically, the Commodore PET, which Byte called the first . The design of the Commodore PET, a single integrated machine with a built in monitor, keyboard, and datasette device, and a character set that made graphics easy to produce, went on to inspire the popular Macintosh computer, by Apple.

Apple II

Steve Wozniak (Woz), a regular visitor to Homebrew Computer Club meetings, designed the Apple I, a single-board computer and first demonstrated it there. With specifications in hand and an order for 100 machines at US$666.66 each from the Byte Shop, Woz and his friend Steve Jobs, founded Apple Computer.

About 200 of the machines sold before the company announced the Apple II as a complete computer. Its higher price and lack of floating point BASIC along with a lack of retail distribution sites caused it to lag in sales behind the TRS-80, its clones, Commodore PET and other machines until 1979 when it surpassed the PET 2001 but was again pushed into 4th when Atari introduced its popular Atari 8-bit. This may be surprising that it wasn't the leader in the late 1970s given that it's now an iconic status symbol of the personal computing phenomenon and had colour graphics, high build quality and open architecture.

The original Apple II operating system was only the built-in BASIC interpreter contained in ROM. Apple DOS was added to support the diskette drive; the last version was "Apple DOS 3.3". The machine came with a built-in full QWERTY keyboard in the flat streamline plastic case. The monitor and I/O devices were sold separately.

More than 4 million Apple II's were shipped by the end of its production in 1993.

PET

Chuck Peddle designed the Commodore PET (Personal Electronic Transactor). It was essentially a single-board computer with a new display chip (the MOS 6545) driving a small built-in monochrome monitor with 40×25 character graphics. It came in 2 models; the 2001-4 with 4kb or the 2001-8 with 8kb of RAM. The machine also included a built-in Datassette for data storage located on the front of the case, which left little room for the keyboard. The 2001 was announced in June 1977 and the first 100 units were shipped in mid October 1977. However they remained back-ordered for months, and to ease deliveries they eventually canceled the 4 kB version early the next year.

Although the machine was fairly successful, there were frequent complaints about the tiny calculator-like keyboard, often referred to as a " chiclet keyboard" because the keys resembled the popular gum candy. This was addressed in upgraded "dash N" and "dash B" versions of the 2001, which put the cassette outside the case, and included a much larger keyboard with a full stroke non-click motion. Internally a newer and simpler motherboard was used, along with an upgrade in memory to 8, 16, or 32 KB, known as the 2001-N-8, 2001-N-16 or 2001-N-32, respectively.

The PET was the least successful with under 1 million sales.

TRS-80

From unknown designers came the TRS-80 which was Tandy Corporation's desktop microcomputer model line sold through Tandy's RadioShack stores in the late-1970s and 1980s. Hobbyists, home users, and small-businesses were the intended consumers. It was nicknamed "trash-eighty" which was both a term of endearment and an insult. No matter for the popularity of the TRS-80 computer with its users resulted in a successful venture for Tandy Corporation. Tandy had 3000+ Radio Shack storefronts from which to retail the TRS-80 while the PET and Apple ][ were mostly mail-order machines. This helped give it the leading position in the 1977 Trinity years.

The Model I combined the motherboard and keyboard into one unit with a separate power supply unit. It used a Zilog Z80 processor clocked at 1.77 MHz (the latest models were shipped with a Z80A). The basic model originally shipped with 4 KB of RAM, and later 16 KB. Its other strong features were its full stroke QWERTY keyboard, small size, well written Floating BASIC and it came with a monitor and tape deck all for $599 a savings of $600 over the Apple II. Its major draw back was the massive RF interference it caused in surrounding electronics which was never solved and was a violation of FCC regulations.

About 1.5 million TRS-80's were sold before its cancellation in 1985

Into homes

As costs continued to drop, home usage began to take off. The initial models such as Sinclairs ZX80 were unimpressive and hence sold only in relatively small numbers. although Its successor, the ZX81 sold in large numbers outside the USA, but it was with the introduction of home computers capable of playing more complex games, in colour with sound, such as the Atari and ZX Spectrum that opened millions of front doors to home computing.

Atari 400/800

In 1979 Atari 400 and Atari 800 introduced the ROM cartridge similar to the Atari 2600 game console to the microcomputer. This allowed pre-made applications in cartridge form to be sold which could be inserted and executed in seconds--a great advantage over cassette-tape installs. The names originally referred to the amount of memory, 4 KB RAM in the 400 and 8 KB in the 800. These two machines had design differences with the 400 being cheaper and targeting a game console niche while the 800 targeted the personal computer niche. The 400 had a membrane keyboard, no memory expansion slots and a single ROM cartridge slot. The 800 had a full-stroke QWERTY, an external memory slot and 2 ROM cartridge slots. They both came with a proprietary (and expensive) serial interface called Serial Input/Output (SIO). All external devices were connected using this interface in a daisy-chain fashion. Microsoft BASIC was 12 KB, and all of Atari's attempts to pare it down to 8 KB failed. So a local consulting firm delivered 8kb Atari BASIC which came on a ROM cartridge.

These two machines sold over 2 million boxes by the end of their production life.

Vic 20 and Commodore 64

Commodore added the ROM cartridge to its designs and produced the VIC-20, which had a full typewriter keyboard, colour and sound, 3.5K of user accessible memory, one side ROM cartridge port and a much lower price than Apple's offerings. It was a successful home computer and sold over 1 million units but was replaced by the Commodore 64.

The best-selling personal computer of all time was released by Commodore International in 1982: the Commodore 64 (C64) . Magazines such as Compute! became available which contained the code for various utilities and games. Both machines connected to a TV set and needed an external tape deck or floppy disk sold separately. The C=64 name derived from it's 64kb of RAM and it also came with a side mount ROM cartridge slot. It used the MOS Technology 6502 microprocessor CPU; MOS Technology, Inc. was owned by Commodore. The C64 and Commodore's other 8-bit computers were followed in 1985 by the more powerful Commodore Amiga 1000, built around the Motorola 68000 CPU.

The Commodore 64 sold over 17 million units before its end.

Back to business

It was the launch of the VisiCalc spreadsheet, initially for the Apple II (and later for the Atari 8-bit family, Commodore PET, and IBM PC) that turned the microcomputer into a business tool. In fact, An Apple employee discovered in 1980 that IBM's San Jose research lab had purchased several Apple IIs, solely to run VisiCalc.

This was followed by the August 12, 1981 release of the IBM PC, which would revolutionize the computer market. The Lotus 1-2-3, a combined spreadsheet (inspired by VisiCalc), presentation graphics, and simple database application, would become the PC's own killer application. Good word processor programs didn't appear for personal computers until 1985. The earlier versions were dominated by WordStar but were not comparable to standalone word processors or those found on mini-computers. WordPerfect 4.1 for the IBM 5150 and Microsoft Word 1.0 for the Apple Macintosh both released in 1985 were enough reason to justify the entire cost of purchasing the computers for individual office workers giving these programs the status of killer applications.

On the January 3, 1983 issue of Time magazine, the personal computer was named the " Person of the Year" for 1982.

The IBM PC

In 1980, IBM decided to enter the personal computer market in response to the success of the Apple II. The first model was the IBM PC, released in August, 1981. Like the Apple II and S-100 systems, it was based on an open, card-based architecture, which allowed third parties to develop for it. It used the Intel 8088 CPU running at 4.77 MHz, containing 29000 transistors. The first model used an audio cassette for external storage, though there was an expensive floppy disk option. While the original PC design could accommodate only up to 64k on the main board, the architecture was able to accommodate up to 640KB of RAM, with the rest on cards. Later revisions of the design increased the limit to 256K on the main board.

The IBM PC typically came with PC-DOS, an operating system based upon Gary Kildall's CP/M-80 operating system. In 1980, IBM approached Digital Research, Kildall's company, for a version of CP/M for its upcoming IBM PC. Kildall's wife and business partner, Dorothy McEwen, met with the IBM representatives who were unable to negotiate a standard non-disclosure agreement with her. IBM turned to Bill Gates, who was already providing the ROM BASIC interpreter for the PC. Gates offered to provide 86-DOS, developed by Tim Paterson of Seattle Computer Products. IBM rebranded it as PC-DOS, while Microsoft sold variations and upgrades as MS-DOS.

The impact of the Apple II and the IBM PC was fully demonstrated when Time magazine named the home computer the "Machine of the Year", or Person of the Year for 1982 (January 3, 1983, "The Computer Moves In"). It was the first time in the history of the magazine that an inanimate object was given this award.

IBM PC clones

The original PC design was followed up in 1983 by the IBM XT, which was an incrementally improved design; it omitted support for the cassette, had more card slots, and was available with an optional hard drive. While the architectural memory limit of 640K was the same, later versions were more readily expandable.

Although the PC and XT included a version of the BASIC language in read-only memory, most were purchased with disk drives and run with an operating system; three operating systems were initially announced with the PC. One was CP/M-86 from Digital Research, the second was PC-DOS from IBM, and the third was the UCSD p-System (from the University of California at San Diego). PC-DOS was the IBM branded version of an operating system from Microsoft, previously best known for supplying BASIC language systems to computer hardware companies. When sold by Microsoft, PC-DOS was called MS-DOS. The UCSD p-System OS was built around the Pascal programming language and was not marketed to the same niche as IBM's customers. Neither the p-System nor CPM-86 was a commercial success.

Because MS-DOS was available as a separate product, some companies attempted to make computers available which could run MS-DOS and programs. These early machines, including the ACT Apricot, the DEC rainbow 100, the Hewlett-Packard HP-150, the Seequa Chameleon and many others were not especially successful, as they required a customized version of MS-DOS, and could not run programs designed specifically for IBM's hardware. See List of early non-IBM-PC-compatible PCs.

Because the IBM PC was based on relatively standard integrated circuits, and the basic card-slot design was not patented, the key portion of that hardware was actually the BIOS software embedded in read-only memory. The first truly IBM PC compatible machines came from Compaq, although others soon followed.

In 1984, IBM introduced the IBM Personal Computer/AT (more often called the PC/AT or AT) built around the Intel 80286 microprocessor. This chip was much faster, and could address up to 16MB of RAM but only in a mode that largely broke compatibility with the earlier 8086 and 8088. In particular, the MS-DOS operating system was not able to take advantage of this capability. A popular urban legend has Bill Gates of Microsoft stating "Why would anyone need more than 640KB?".

Xerox Alto and Star

The Xerox Alto, developed at Xerox PARC in 1973, was a small minicomputer, and the first computer to use a mouse, the desktop metaphor, and a graphical user interface (GUI), concepts first introduced by Douglas Engelbart while at SRI International.

While its use was limited to the engineers at Xerox PARC, the Alto had features years ahead of its time and would later serve, along with the Xerox Star, as a model for the Apple Macintosh.

Introduced in 1981, the Xerox Star workstation, officially known as the "8010 Star Information System" was introduced by Xerox Corporation. Drawing upon its predecessor, The Xerox Alto, it was the first commercial system to incorporate various technologies that today have become commonplace in personal computers, including a bit-mapped display, a windows-based graphical user interface, icons, folders, mouse, Ethernet networking, file servers, print servers and e-mail. It also included a programming language system called Smalltalk.

Both the Xerox Alto and the Xerox Star would inspire the Apple Lisa and the Apple Macintosh.

Others

The Processor Technology Corporation produced the Sol-20 in 1976 and although it only sold 10,000 units it is significant because it had all the parts to be a stand-alone micro-computer. It came with a full QWERTY keyboard, storage tapedeck, 12" monochrome monitor and housed in a walnut paneled case with a power supply. It was built on the Intel 8080 CPU and had the standard S100 hardware bus giving it access to expansion cards and came with BASIC programming language all for $2100.

Many other home computers came onto the market, including the Atari 8-bit family, the Sinclair ZX80 and successors ZX81, ZX Spectrum and QL, the TI 99/4A, the BBC Micro, the Amstrad/Schneider CPC 464/CPC 646/CPC 6128 family, the Oric Atmos, the Coleco Adam, the SWTPC 6800 and 6809 machines, the Tandy Colour Computer/ Dragon 32/64, the Exidy Sorcerer, and the Japanese MSX range.

Of these, the Sinclair and BBC models were very influential in the British market, with the former introduced at an exceptional low cost (under £100), and the latter developed to meet the BBC and UK government's goals of introducing computer literacy to all schools and elsewhere in education and becoming widely popular in the home.

Apple Lisa and Macintosh

In 1983 Apple Computer introduced the first mass-marketed microcomputer with a graphical user interface, the Lisa. The Lisa ran on a Motorola 68000 microprocessor and came equipped with 1 megabyte of RAM, a 12-inch (300 mm) black-and-white monitor, dual 5¼-inch floppy disk drives and a 5 megabyte Profile hard drive. The Lisa's slow operating speed and high price (US$10,000), however, led to its commercial failure. It also led to the decision by Steve Jobs to move to the Apple Macintosh team.

Drawing upon its experience with the Lisa, in 1984 Apple launched the Macintosh. Its debut was announced by a single broadcast during the 1984 Super Bowl XVIII of the now famous television commercial "1984" created by Ridley Scott and based on George Orwell's novel 1984. The intention of the ad was to equate Big Brother with the IBM PC and a nameless female action hero ( Anya Major), with the Macintosh.

The Mac was the first successful mouse-driven computer with a graphical user interface or 'WIMP' (Windows, Icons, Menus, and Pointers). Based on the Motorola 68000 microprocessor, the Macintosh included many of the Lisa's features at a price of $2,495. The Macintosh was initially introduced with 128 kb of RAM and later that year a 512 kb RAM model became available. To reduce costs of the Lisa the year younger Mac had a simplified motherboard design, no internal hard drive, and a single 3.5" floppy drive. Applications that came with the Macintosh included MacPaint, a bit-mapped graphics program, and MacWrite, which demonstrated WYSIWYG word processing.

While not an immediate success upon its release, the Macintosh was a successful personal computer for years to come. This is particularly due to the introduction of desktop publishing in 1985 through Apple's partnership with Adobe. This partnership introduced the LaserWriter printer and Aldus PageMaker (now Adobe PageMaker) to users of the personal computer. After Steve Jobs resigned from Apple in 1985 to start NeXT, a number of different models of Macintosh were released to a great degree of success such as the Macintosh Plus and Macintosh II. The entire Macintosh line of computers was IBM's major competition up until the early 1990s.

Other graphical computers

In 1985, the Atari ST, also based on the Motorola 68000 microprocessor, was introduced with the first colour GUI in the Atari TOS. It could be modified to emulate the Macintosh using the third-party Spectre GCR device.

In the Commodore world, GEOS was available on the Commodore 64 and Commodore 128. Later, a version was available for PCs running DOS. It could be used with a mouse or a joystick as a pointing device, and came with a suite of GUI applications. Commodore's later product line, the Amiga platform, ran a GUI operating system by default.

In 1987, Acorn launched the Archimedes range of high-performance home computers in Europe and Australasia. Based around their own 32-bit ARM RISC processor, the systems initially shipped with a GUI OS called Arthur. In 1989, Arthur was superseded by a multi-tasking GUI-based operating system called RISC OS. By default, the mice used on these computers had three buttons.

PC Clones Dominate

The transition from a PC-compatible market being driven by IBM to one driven primarily by a broader market began to become clear in 1986 and 1987; in 1986, the 32-bit Intel 80386 microprocessor was released, and the first '386-based PC-compatible was the Compaq Deskpro 386. IBM's response came nearly a year later with the initial release of the IBM Personal System/2 series of computers, which had a closed architecture and were a significant departure from the PC standard. These models were largely unsuccessful, and the PC Clone style machines outpaced sales of all other machines through the rest of this period.

1990s and 2000s

In 1990, the NeXTstation workstation computer went on sale, for "interpersonal" computing as Steve Jobs described it. The NeXTstation was meant to be a new computer for the 1990s, and was a cheaper version of the previous NeXT Computer. The NeXTstation was somewhat a commercial failure, and NeXT shut down hardware operations in 1993.

The early 1990s saw the advent of the CD ROM coming as an industry standard, built-in to many desktop computers, and towards the end of the 1990s, in laptops as well. Although introduced in 1982, the CD ROM was mostly used for audio during the 1980s (and also video as the LaserDisc), and then for computer data such as operating systems and applications into the 1990s. Another popular use of CD ROMs in the 1990s was multimedia, as many desktop computers started to come with built-in stereo speakers capable of playing CD quality music and sounds with the SoundBlaster sound card on PCs. Later, CD-RW drives were included instead of standard CD ROM drives.

IBM introduced its successful ThinkPad range at Comdex 1992 using the series designators 300, 500 and 700 (allegedly analogous to the BMW car range and used to indicate market), the 300 series being the "budget", the 500 series "midrange" and the 700 series "high end". This designation continued until the late 1990's when IBM introduced the "T" series as 600/700 series replacements, and the 3,5 and 7 series model designations were phased out for A (3&7) & X (5) series. The A series was later partially replaced by the R series.

In 1994, The Zip drive was introduced by Iomega as a medium-capacity removable disk storage system. It aimed to replace the standard 3.5-inch (89 mm) floppy disk but failed to do so. Before the Zip was introduced, SyQuest was popular in the market of removable media, but were expensive and largely unsuccessful due to reliability issues. More modern Zip drives are still being produced into the latter 2000s, however writable CDs are more common.

By the mid 1990s, Amiga, Commodore and Atari systems were no longer on the market, pushed out by strong IBM PC clone competition and low prices. Other previous competition such as Sinclair and Amstrad were no longer in the computer market. With less competition than ever before, Dell rose to high profits and success, introducing low-cost systems targeted at consumers and business markets using a direct-sales model. Dell surpassed Compaq as the world's largest computer manufacturer, and held that position until October 2006.

In 1994, Apple introduced the Power Macintosh series of high-end professional desktop computers for desktop publishing and graphic designers. These new computers made use of new Motorola PowerPC processors as part of the AIM alliance, to replace the previous Motorola 68k architecture used for the Macintosh line. During the '90s, the Macintosh remained with a low market share, but as the primary choice for creative professionals, particularly those in the graphics and publishing industries.

Also in 1994, Acorn Computers launched its Risc PC series of high-end desktop computers. The Risc PC (codenamed Medusa) was Acorn's next generation ARM-based RISC OS computer, which superseded the Acorn Archimedes.

In 1995, Be Inc. released the BeBox computer, which used a dual PowerPC processor running at 66 MHz, and later 133 MHz with the Be operating system. The BeBox was largely a failure, with fewer than 2000 units produced between October 1995 and January 1997, when production was ceased.

Due to the growth amongst IBM cloners in the '90s, they became the industry standard for business and home use, and with the introduction of Microsoft's Windows 3.0 operating system in 1990, and later with Windows 95 in 1995. The Macintosh was sent into a period of decline by the mid 1990s, and by 1996, Apple was almost bankrupt. Steve Jobs returned to Apple in 1997, and brought Apple back into profitability, firstly with the release of Mac OS 8, a new operating system for Macintoshes, and with the PowerMac G3 and iMac computers for the professional and home markets. The iMac was one of the first computers to not use the beige colour for casing, but a transparent bondi blue in an ergonomic shape, the iMac sold several million units and is still in production as of late 2007 using a different form factor. Mac OS X, iLife and iBook were later introduced by Apple.

The first PC motherboards to support Rambus RDRAM (Rambus Direct DRAM), a type of synchronous dynamic RAM, were released in 1999. RDRAM was also two to three times the price of PC-133 SDRAM due to a combination of high manufacturing costs and high license fees. RDRAM is very rarely used today.

Towards the late 1990s, many more personal computers started shipping that included USB (Universal Serial Bus) ports for easy plug and play connectivity to devices such as digital cameras, video cameras, personal digital assistants, printers, scanners, USB flash drives and other peripheral devices. As of 2006, all currently shipping computers for the consumer market include at least 2 USB ports. Also during the latter 1990s, DVD players started appearing on higher-end, usually more expensive, desktop and laptop computers, and eventually on consumer computers into the 2000s.

In 2002, Hewlett-Packard (HP) purchased Compaq. Compaq itself had bought Tandem Computers in 1997 (which had been started by ex-HP employees), and Digital Equipment Corporation in 1998. Following this strategy HP became a major player in desktops, laptops, and servers for many different markets. The buyout made HP the world's largest manufacturer of personal computers, until Dell later surpassed HP.

In 2003, AMD shipped its 64-bit based microprocessor line for desktop computers, Opteron and Athlon 64. Also in 2003, IBM released the 64-bit based PowerPC 970 for Apple's high-end PowerMac G5 systems. Intel, in 2004, reacted to AMD's success with 64-bit based processors, releasing updated versions of their Xeon and Pentium 4 lines. 64-bit processors are common in high end systems, servers and workstations, but are slowly becoming more popular in consumer desktop systems.

In 2004, IBM announced the proposed sale of its PC business to Chinese computer maker Lenovo Group, which is partially owned by the Chinese government, for $650 million US in cash and $600 million US in Lenovo stock. The deal was approved by the Committee on Foreign Investment in the United States in March 2005, and completed in May 2005. IBM will have a 19% stake in Lenovo, which will move its headquarters to New York State and appoint an IBM executive as its chief executive officer. The company will retain the right to use certain IBM brand names for an initial period of five years. As a result of the purchase, Lenovo inherited a product line that featured the ThinkPad, a line of laptops that had been one of IBM's most successful products.

In the early 2000s, WiFi began to become increasingly more popular as many consumers started installing their own wireless home networks. Many of today's laptops and also desktop computers are sold pre-installed with wireless cards and antennas. Also in the early 2000s, LCD monitors became more popular for computer monitors, with CRT production being slowed down. LCD monitors are typically sharper, brighter, and more economical than CRT monitors. The 2000s also saw the rise of multi-core processors and flash memory. Once limited to high-end industrial use due to expense, these technologies are now mainstream and available to consumers.

Microprocessor-Based Server and Networks

The invention in the late 1970s of local area networks (LANs), notably Ethernet, allowed PCs to communicate with each other ( peer-to-peer) and with shared printers.

As the microcomputer revolution continued, more robust versions of the same technology were used to produce microprocessor based servers that could also be linked to the LAN. This was facilitated by the development of server operating systems to run on the Intel architecture, including several versions of both Unix and Microsoft Windows.

With the development of storage area networks and server farms of thousands of servers, by the year 2000 the minicomputer had all but disappeared, and mainframes were largely restricted to specialized uses. The Google server farm is thought to be the largest, with a total calculation rate three times that of Earth Simulator or Blue Gene, as of September 29, 2004.

Uses

Personal computers are normally operated by one user at a time to perform such general purpose tasks as word processing, Internet browsing, Internet faxing, e-mail and other digital messaging, multimedia playback, computer game play, computer programming, etc. The user of a modern personal computer may have significant knowledge of the operating environment and application programs, but is not necessarily interested in programming nor even able to write programs for the computer. Therefore, most software written primarily for personal computers tends to be designed with simplicity of use, or " user-friendliness" in mind. However, the software industry continuously provide a wide range of new products for use in personal computers, targeted at both the expert and the non-expert user.

Configuration

This section describes the typical personal computer called a desktop computer because one can easily look inside the case. The other types of personal computers have the same basic setup, but usually lack the peripherals.

Computer components

A minimal setup of a typical contemporary desktop computer would be

• Computer case with power supply (usually sold together)
• Motherboard
• Processor with a heat sink and fan (usually sold together)
• At least one memory card
• Mass storage
• Keyboard and mouse for input
• Monitor for output

The motherboard connects everything together. The memory card(s), graphics card and processor, are mounted directly onto the motherboard (the processor in a socket and the memory and graphics cards in expansion slots). The mass storage is connected to it with cables and can be installed in the computer case or in a separate case. Same for keyboard and mouse, except that they are external and connect to the I/O panel on the back of the computer. The monitor is also connected to the I/O panel, either through an onboard port on the motherboard, or a port on the graphics card.

The mass storage can be

• Hard disk
• Floppy drive or Zip drive (both with removable media)
• Optical drive (CD or DVD, removable, usually read-only)
• Flash Storage (interal or memory card)

The operating system (e.g.: Microsoft Windows, Mac OS, Linux or many others) can be located on either of these, but typically it's on one of the hard disks. A LiveCD is also possible, but it is very slow and is usually used for installation of the OS, demonstrations, or problem solving.

On top of these, a computer may also have

• Sound card
• Video card
• Network card
• internal modem card (although less frequently these days).

Common additions, connected on the outside ( peripherals), are

• Printer
• Scanner
• Webcam
• Speakers
• Microphone
• Modem
• router
• Headset
• Card reader
• Gaming devices such as a joystick

Several functions (implemented by chipsets) can be integrated into the motherboard, such as typically USB and network, but also graphics and sound. But even if these are present, a separate card can be added if what is available isn't sufficient.

The graphics and sound card can have a break out box to keep the analog parts away from the electromagnetic radiation inside the computer case. For really large amounts of data, a tape drive can be used or (extra) hard disks can be put together in an external case.

These components can usually be put together with little knowledge, to build a computer. If something shouldn't go somewhere, it usually doesn't fit (this used to not always be the case in the past) and if it does fit it can usually do little harm.

Most personal computers are standardized to the point that purchased software is expected to run with little or no customization for the particular computer. Many PCs are also user-upgradeable, especially desktop and workstation class computers. Devices such as main memory, mass storage, even the motherboard and central processing unit may be easily replaced by an end user. This upgradeability is, however, not indefinite due to rapid changes in the personal computer industry. A PC that was considered top-of-the-line five or six years prior may be impractical to upgrade due to changes in industry standards. Such a computer usually must be totally replaced once it's no longer suitable for its purpose. This upgrade and replacement cycle is partially related to new releases of the primary mass-market operating system, which tends to drive the acquisition of new hardware and tends to obsolete previously serviceable hardware (see planned obsolescence).

The hardware capabilities of personal computers can sometimes be extended by the addition of expansion cards connected via an expansion bus. Some standard peripheral buses often used for adding expansion cards in personal computers as of 2005 are PCI, AGP (a high-speed PCI bus dedicated to graphics adapters), and PCI Express. Most personal computers as of 2005 have multiple physical PCI expansion slots. Many also include an AGP bus and expansion slot or a PCI Express bus and one or more expansion slots, but few PCs contain both buses.

Motherboard

The motherboard (or mainboard) is the primary circuit board within a personal computer. Many other components connect directly or indirectly to the motherboard. Motherboards usually contain one or more CPUs, supporting circuitry -- usually integrated circuits (ICs) providing the interface between the CPU memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after being powered on (often called boot firmware or, in IBM PC compatible computers, a BIOS). In many portable and embedded personal computers, the motherboard houses nearly all of the PC's core components. Often a motherboard will also contain one or more peripheral buses and physical connectors for expansion purposes. Sometimes a secondary daughter board is connected with the motherboard to provide further expandability or to satisfy space constraints..

Central processing unit

The central processing unit, or CPU, is that part of a computer which executes software program instructions. In older computers this circuitry was formerly on several printed circuit boards, but in PC class machines, has been from the first personal computers, a single integrated circuit. Nearly all PCs contain a type of CPU known as a microprocessor. The microprocessor often plugs into the motherboard using one of many different types of socket. IBM PC compatible computers use an x86-compatible processor, usually made by Intel, AMD, VIA Technologies or Transmeta. Apple Macintosh computers were initially built with the Motorola 680x0 family of processors, then switched to the PowerPC series (a RISC architecture jointly developed by Apple Computer, IBM and Motorola), but as of 2006, Apple has switched again, this time to x86 compatible processors.

Main memory

A PC's main memory (i.e., its 'primary store') is fast storage that is directly accessible by the CPU, and is used to store the currently executing program and immediately needed data. PCs use semiconductor random access memory (RAM) of various kinds such as DRAM or SRAM as their primary storage. Which exact kind depends on cost/performance issues at any particular time. Main memory is much faster than mass storage devices like hard disks or optical discs, but is usually volatile, meaning it does not retain its contents (instructions or data) in the absence of power, and is much more expensive for a given capacity than is most mass storage. Main memory is generally not suitable for long-term or archival data storage.

Mass storage

Mass storage devices store programs and data even when the power is off; they do require power to perform read/write functions during usage. Although semiconductor flash memory has dropped in cost, the prevailing form of mass storage in personal computers is still the electromechanical hard disk.

The disk drives use a sealed head/disk assembly (HDA) which was first introduced by IBM's "Winchester" disk system. The use of a sealed assembly allowed the use of positive air pressure to drive out particles from the surface of the disk, which improves reliability.

If the mass storage controller provides for expandability, a PC may also be upgraded by the addition of extra hard disk or optical disc drives. For example, DVD-ROMs, CD-ROMs, and various optical disc recorders may all be added by the user to certain PCs. Standard internal storage device interfaces are ATA, Serial ATA, SCSI, and CF+ Type II in 2005.

Video card

The video card - otherwise called a graphics card, graphics adapter or video adapter - processes and renders the graphics output from the computer to the computer display, also called the visual display unit (VDU), and is an essential part of the modern computer. On older models, and today on budget models, graphics circuitry tended to be integrated with the motherboard but, for modern flexible machines, they are supplied in PCI, AGP, or PCI Express format.

When the IBM PC was introduced, many existing personal computers used text-only display adapters and had no graphics capability.

Laptop computers

A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for mobility. Usually all of the interface hardware needed to operate the laptop, such as parallel and serial ports, graphics card, sound channel, etc., are built in to a single unit. Most laptops contain batteries to facilitate operation without a readily available electrical outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine.

One main drawback of the laptop is that, due to the size and configuration of components, relatively little can be done to upgrade the overall computer from its original design. Some devices can be attached externally through ports (including via USB); however internal upgrades are not recommended or in some cases impossible, making the desktop PC more modular.