The history of personal computers as mass-market consumer electronic devices began with the microcomputer revolution of the 1970s. A personal computer is one intended for interactive individual use, as opposed to a mainframe computer where the end user's requests are filtered through operating staff, or a time-sharing system in which one large processor is shared by many individuals.
After the development of the microprocessor, individual personal computers were low enough in cost that they eventually became affordable consumer goods. Early personal computers – generally called microcomputers – were sold often in electronic kit form and in limited numbers, and were of interest mostly to hobbyists and technicians.
Etymology There are several competing claims as to the origins of the term "personal computer". Yale Law School librarian Fred Shapiro notes an early published use of the phrase in a 1968 Hewlett-Packard advertisement for a programmable calculator, which they called "The new Hewlett-Packard 9100A personal computer." Other claims include computer pioneer Alan Kay's purported use of the term in a 1972 paper, Whole Earth Catalog publisher Stewart Brand's usage in a 1974 book, MITS co-founder Ed Roberts' usage in 1975, and Byte magazine's May 1976 usage of "[in] the personal computing field" in its first edition. In 1975, 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."
Overview
The history of the personal computer as mass-market consumer electronic devices effectively began in 1972 with the introduction of microcomputers, although some mainframe and minicomputers had been applied as single-user systems much earlier. A personal computer is one intended for interactive individual use, as opposed to a mainframe computer where the end user's requests are filtered through operating staff, or a time sharing system in which one large processor is shared by many individuals. After the development of the microprocessor, individual personal computers were low enough in cost that they eventually became affordable consumer goods. Early personal computers – generally called microcomputers – were sold often in electronic kit form and in limited numbers, and were of interest mostly to hobbyists and technicians.
Mainframes, minicomputers, and microcomputers Computer terminals were used for time sharing access to central computers. 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 generally 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 center 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.Anthony Ralston and Edwin D. Reilly (ed), Encyclopedia of Computer Science 3rd Edition, Van Nostrand Reinhold, 1993 , article Digital Computers History In places such as Carnegie Mellon University and MIT, students with access to some of the first computers experimented with applications that would today be typical of a personal computer; for example, computer-aided design and drafting was foreshadowed by T-square, a program written in 1961, and an ancestor of today's computer games was found in Spacewar! in 1962.
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). 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 center.
In 1945, Vannevar Bush published an essay called "As We May Think" in which he outlined a possible solution to the growing problem of information storage and retrieval. In 1968, SRI researcher Douglas Engelbart gave what was later called "The Mother of All Demos", in which he offered a preview of things that have become the staples of daily working life in the 21st century: e-mail, hypertext, word processing, video conferencing, and the mouse. The demo was the culmination of research in Engelbart's Augmentation Research Center laboratory, which concentrated on applying computer technology to facilitate creative human thought.
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.Rheingold, H. (2000). Tools for thought: the history and future of mind-expanding technology (New ed.). Cambridge, MA etc.: The MIT Press.
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.
The single-chip microprocessor was made possible by an improvement in MOS technology: the silicon-gate MOS chip, developed in 1968 by Federico Faggin, who later used silicon-gate MOS technology to develop the first single-chip microprocessor, the Intel 4004, in 1971.
A few researchers at places such as SRI and Xerox PARC were working on computers that a single person could use and that could be connected by fast, versatile networks: not home computers, but personal ones. At RCA, Joseph Weisbecker designed and built a true home computer known as FRED, but this saw mixed interest from management. The CPU design was released as the COSMAC in 1974 and several experimental machines using it were built in 1975, but RCA declined to market any of these until introducing the COSMAC Elf in 1976, in kit form. By this time a number of other machines had entered the market.
After the introduction of the Intel 4004 in 1972, microprocessor costs declined rapidly. In 1974 the American electronics magazine Radio-Electronics described the Mark-8 computer kit, based on the Intel 8008 processor. In January 1975, Popular Electronics magazine published an article describing a kit based on the Intel 8080, a somewhat more powerful and easier to use processor. The Altair 8800 sold remarkably well, even though initial memory size was limited to a few hundred bytes and there was no software available.
However, the Altair kit was much less costly than an Intel development system of the time and so was purchased by companies interested in developing microprocessor control for their own products. Expansion memory boards and peripherals were soon listed by the original manufacturer, and later by plug compatible manufacturers.
The very first Microsoft product was a 4 kilobyte paper tape BASIC interpreter, which allowed users to develop programs in a higher-level language. The alternative was to hand-assemble machine code that could be directly loaded into the microcomputer's memory using a front panel of toggle switches, push buttons and LED displays. While the hardware front panel emulated those used by early mainframe and minicomputers, after a very short time I/O through a terminal was the preferred human/machine interface, and front panels became extinct.
The beginnings of the personal computer industry
Simon
Simon was a small electro-mechanical computer project developed by Edmund Berkeley and presented in a thirteen-article series in Radio-Electronics magazine from October 1950. The Simon was in some sense a personal computer, although it was not of much practical use. The four-function ALU was only 2 bits wide, meaning it was not capable of operating on any number greater than 3. There were far more sophisticated and practical computers available at the time (such as EDSAC), and the kit was intended only as an educational machine for hobbyists to learn about the operation and design of a digital computer. The value in Simon was that the digital principles learnt could be scaled up to the task of building a larger and more useful machine.What was the first personal computer? at Blinkenlights Archaeological Institute. Accessed: 15 March 2008.
LGP-30
The LGP-30 was an off-the-shelf vacuum-tube computer manufactured by the Librascope company of Glendale, California. The LGP-30 was first manufactured in 1956, at a retail price of $47,000. The LGP-30 was commonly referred to as a desk computer, as it was the size of a desk. It weighed about 800 pounds (360 kg). It was a binary, 31-bit word computer with a 4096-word drum memory. Standard inputs were the Flexowriter keyboard and paper tape. The standard output was the Flexowriter typewriter. Up to 493 units were produced.
IBM 610
The IBM 610 was a vacuum-tube computer designed by John Lentz at the Watson Lab of Columbia University. It was announced by IBM as the 610 Auto-Point in 1957. The machine consisted of a large cabinet but could fit in a conventional office and required no specialist arrangements for air conditioning or power. It was intended to be used by only one operator and was symbolically programmable using a keyboard. With a price tag of $55,000, only 180 units were produced and it was quickly displaced by the transistorized IBM 1620.
LINC
The LINC (Laboratory INstrument Computer) was an early minicomputer first produced in 1962 at MIT's Lincoln Laboratory. The machine was intended for use in biomedical research applications. The LINC consisted of a large unit that could fit on a desk with keyboard input and a monitor screen constructed from an oscilloscope, although it required a second chassis about the size of a wardrobe that contained the CPU and memory.
Despite its size, the LINC had the nascent characteristics of a personal computer, being one of the first machines specifically intended to serve a single user as opposed to being a shared resource. Machines of the day were most usually extremely large fixed installations. The LINC was just barely portable to another location by a single person. It was possible to disassemble and fit all of the apparatus into a car and assemble it in a reasonable time for use elsewhere without the support of a computer lab.