The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid state devices such as the transistor and later the integrated circuit. By 1959 discrete transistors were considered sufficently reliable and economical that they made further vacuum tube computers uncompetetive. Computer main memory slowly moved away from magnetic core memory devices to solid-state static and dynamic semiconductor memory, which greatly reduced the cost, size and power consumption of computer devices. Eventually the cost of integrated circuit devices became low enough that home computers and personal computers became widespread.

Third generation

The mass increase in the use of computers accelerated with 'Third Generation' computers. These typically relied on Jack St. Claire Kilby's invention of the integrated circuit (or microchip), starting around 1965. However, the IBM System/360 used hybrid circuits, which were solid-state devcies interconnected on a substrate with discrete wires.

The first integrated circuit was produced in September 1958 but computers using them didn't begin to appear until 1963. Some of their early uses were in embedded systems, notably used by NASA for the Apollo Guidance Computer and by the military in the LGM-30 Minuteman intercontinental ballistic missile.

By 1971, the Illiac IV supercomputer, which was the fastest computer in the world for several years, used about a quarter-million small-scale ECL logic gate integrated circuits to make up sixty-four parallel data processors.

While large 'mainframes' such as the System/360 increased storage and processing capabilities, the integrated circuit also allowed the development of much smaller computers. The minicomputer was a significant innovation in the 1960s and 1970s. It brought computing power to more people, not only through more convenient physical size but also through broadening the computer vendor field. Digital Equipment Corporation became the number two computer company behind IBM with their popular PDP and VAX computer systems. Smaller, affordable hardware also brought about the development of important new operating systems like Unix.

Large scale integration of circuits led to the development of very small processing units, an early example of this is the processor was the classified CADC used for analyzing flight data in the US Navy's F14A Tomcat fighter jet. This processor was developed by Steve Geller, Ray Holt and a team from AiResearch and American Microsystems.

In 1966, Hewlett-Packard entered the general purpose computer business with its HP-2116, offering a computational power formerly found only in much larger computers. It supported a wide variety of languages, among them BASIC, ALGOL, and FORTRAN.1969: Data General Nova.

In 1969, Data General shipped a total of 50,000 Novas at $8000 each. The Nova was one of the first 16-bit minicomputers and led the way toward word lengths that were multiples of the 8-bit byte. It was first to employ medium-scale integration (MSI) circuits from Fairchild Semiconductor, with subsequent models using large-scale integrated (LSI) circuits. Also notable was that the entire central processor was contained on one 15-inch printed circuit board.

In 1973, the TV Typewriter, designed by Don Lancaster, provided electronics hobbyists with a display of alphanumeric information on an ordinary television set. It used $120 worth of electronics components, as outlined in the September 1973 issue of Radio Electronics magazine. The original design included two memory boards and could generate and store 512 characters as 16 lines of 32 characters. A 90-minute cassette tape provided supplementary storage for about 100 pages of text. His design used minimalistic hardware to generate the timing of the various signals needed to create the TV signal. Clive Sinclair later used the same approach in his legendary Sinclair ZX80.

Fourth generation

The basis of the fourth generation was Marcian Hoff's invention of the microprocessor.

Unlike Third generation minicomputers, which were essentially scaled down versions of mainframe computers, the fourth generation's origins are fundamentally different. Microprocessor-based computers were originally very limited in their computational ability and speed, and were in no way an attempt to downsize the minicomputer. They were addressing an completely different market.

Although processing power and storage capacities have increased beyond all recognition since the 1970s, the underlying technology of LSI (large scale integration) or VLSI (very large scale integration) microchips has remained basically the same, so it is widely regarded that most of today's computers still belong to the fourth generation.

Microprocessors

1971: Intel 4004.

On November 15, 1971, Intel released the world's first commercial microprocessor, the 4004. It was developed for a Japanese calculator company, Busicom, as an alternative to hardwired circuitry. Fourth generation computers developed, using a microprocessor to locate much of the computer's processing abilities on a single (small) chip. Coupled with one of Intel's other products - the RAM chip, based on an invention by Robert Dennard of IBM, (kilobits of memory on a single chip) - the microprocessor allowed fourth generation computers to be even smaller and faster than ever before. The 4004 was only capable of 60,000 instructions per second, but later processors (such as the Intel 8086 upon which all of the IBM PC and compatibles are based) brought ever increasing speed and power to the computers.

Supercomputers

1976: Cray-1 supercomputer.

At the other end of the computing spectrum from the microcomputers, the supercomputers of the era also harnessed integrated circuit technology and were immensely powerful. In 1976 the Cray-1 was developed by Seymour Cray, who left Control Data in 1972 to form his own company. This machine was known as much for its horseshoe-shaped design -- an effort to speed processing by shortening circuit paths -- as it was for being the first supercomputer to make vector processing practical. Vector processing, which uses a single instruction to perform the same operation on many numbers, has been a fundamental supercomputer processing style ever since. The Cray-1 could calculate 150 million floating point operations per second. 85 were shipped at a cost of $5 million each. The Cray-1 had a CPU that was mostly constructed of ECL SSI/MSI circuits.

Microcomputer emerges

Main article: personal computer

The advent of the microprocessor and solid-state memory made personal computers affordable. Early hobby micrcomputer systems such as the Altair 8800 and Apple I introduced around 1975 marked release of low-cost 8-bit processor chips, which had sufficient computing power to be of interest to hobby and experimental users. By 1977 pre-assembled systems such as the Apple II, PET, and TRS 80 began the era of mass-market personal computers; much less assemblywork was required to obtain an operating computer and applications such as games, word processing, and spreadsheets began to proliferate.