First Generation (1940-1956) Vacuum TubesThe first computers used vacuum tubes for circuitry andmagnetic drums for memory, and were often enormous,taking up entire rooms. They were expensive to operateand in addition to using a great deal of electricity,generated a lot of heat, which was often the cause ofmalfunctions. First generation computers relied on machinelanguage, the lowest-level programming languageunderstood by computers, to perform operations, and theycould only solve one problem at a time. Input was based onpunched cards and paper tape, and output was displayed onprintouts. The UNIVAC and ENIAC computers areexamples of first-generation computing devices. TheUNIVAC was the first commercial computer delivered to abusiness client, the U.S. Census Bureau in 1951.
Vacuum tube processing unit in a first-generation computer
Second Generation (1956-1963) TransistorsTransistors replaced vacuum tubes and ushered in the secondgeneration of computers. The transistor was invented in 1947 but didnot see widespread use in computers until the late 1950s. Thetransistor was far superior to the vacuum tube, allowing computers tobecome smaller, faster, cheaper, more energy-efficient and morereliable than their first-generation predecessors. Though thetransistor still generated a great deal of heat that subjected thecomputer to damage, it was a vast improvement over the vacuumtube. Second-generation computers still relied on punched cards forinput and printouts for output. Second-generation computers movedfrom cryptic binary machine language to symbolic, or assembly,languages, which allowed programmers to specify instructions inwords. High-level programming languages were also being developedat this time, such as early versions of COBOL and FORTRAN. Thesewere also the first computers that stored their instructions in theirmemory, which moved from the magnetic drum to magnetic coretechnology. The first computers of this generation were developed forthe atomic energy industry.
Transistor-based processing unit in a second- generation computer
Third Generation (1964-1971) Integrated CircuitsThe development of the integrated circuit was the hallmarkof the third generation of computers. Transistors wereminiaturized and placed on silicon chips, calledsemiconductors, which drastically increased the speed andefficiency of computers. Instead of punched cards andprintouts, users interacted with third generation computersthrough keyboards and monitors and interfaced with anoperating system, which allowed the device to run manydifferent applications at one time with a central programthat monitored the memory. Computers for the first timebecame accessible to a mass audience because they weresmaller and cheaper than their predecessors.
An early IC chip, containing 3 transistors (silver)
Fourth Generation (1971-Present) Microprocessors)The microprocessor brought the fourth generation of computers, asthousands of integrated circuits were built onto a single siliconchip. What in the first generation filled an entire room could nowfit in the palm of the hand. The Intel 4004 chip, developed in 1971,located all the components of computers from the centralprocessing unit and memory to input/output controls on a singlechip. In 1981 IBM introduced its first computer for the home user,and in 1984 Apple introduced the Macintosh. Microprocessors alsomoved out of the realm of desktop computers and into many areasof life as more and more everyday products began to usemicroprocessors. As these small computers became more powerful,they could be linked together to form networks which eventuallyled to the development of the Internet. Fourth generation computersalso saw the development of GUIs, the mouse and handhelddevices.
Fifth Generation (Present and Beyond ArtificialIntelligence)Fifth generation computing devices, based onartificial intelligence, are still in development,though there are some applications, such as voicerecognition, that are being used today. The use ofparallel processing and superconductors is helping tomake artificial intelligence a reality. Quantumcomputation and molecular and nanotechnology willradically change the face of computers in years tocome. The goal of fifth-generation computing is todevelop devices that respond to natural languageinput and are capable of learning and selforganization.