Thursday, January 18, 2007

Computers at home

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. Forty years later, many boys and girls owned and used personal computers.

The minicomputer ancestors of the modern personal computer did not use microprocessors, which explained their size and high cost. After the commercialization of the "computer-on-a-chip", the cost of manufacture of a computer system dropped dramatically. The arithmetic, logic, and control functions that previously occupied several costly circuit boards were now available in integrated form. Concurrently, advances in the development of solid-state memory eliminated the bulky, costly, and power-consuming core storage used in prior generations of computers.

A programmable terminal called the Datapoint 2200 is the earliest known device that bears any significant resemblance to the modern personal computer. 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.

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 December 1974 issue, at the time set a new low price point for a computer, bringing computer ownership to an admittedly select market in the 1970s. It was arguably this computer that spawned the development of both Apple Computer as well as Microsoft, spawning 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 success of the Steve Wozniak-designed Apple release, the Apple II — were usually known as home computers. These were less capable and in some ways less versatile than large business computers of the day. They were generally used by computer enthusiasts for learning to program, running simple office/productivity applications, electronics interfacing, and general hobbyist pursuits. By the late 1990s, the "home computer" was becoming a less common label in favor of "personal computer." The graphics and sound capacities of "home" systems were matched by those intended for "business" purposes, with a general decrease in costs. The two market segments fused. These computers were pre-assembled, often pre-configured with bundled software, and required little technical knowledge to operate.

Computers

A computer is a machine for manipulating data according to a list of instructions.

Computers take numerous physical forms. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers. Today, computers can be made small enough to fit into a wrist watch and be powered from a watch battery. Society has come to recognize personal computers and their portable equivalent, the laptop computer, as icons of the information age; they are what most people think of as "a computer". However, the most common form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to control other devices—for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys.

The ability to store and execute programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: Any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks so long as time and storage capacity are not considerations.