Computer Generations & Hierarchies

Introduction: Computer Generations History of development of computers down the years is referred as Computer Generations. A generation refers to research and development done to improve the performance of computers. It also refers to the new technical breakthroughs and advancements in computers. A generation has significantly decreased the size of computers and increased the performance. With the increase in speed, power and memory and decrease in size, each generation has brought down the cost and to be available to the masses. First Generation Time Frame: 1940-1956

The computers in the first generation used vacuum tubes for circuitry and magnetic drums for memory, and were huge in size, taking up entire rooms. A magnetic drum, , is a metal cylinder coated with magnetic iron-oxide material on which data and programs can be stored. These were once used as a primary storage device but have since been implemented as auxiliary storage devices. The tracks on the magnetic drum are referred as channels located around the circumference of the drum, forming adjacent circular bands that wind around the drum. A single drum can have up to 200 tracks.

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As the drum rotates at a speed of up to 3,000 rpm(rotations per minute), the device’s read/write heads deposit magnetized spots on the drum during the write operation and then senses these spots during a read operation. This action is similar to that of a presently used magnetic tape or disk drive. They were very expensive to operate as they use a great deal of electricity, as a result generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time, also known as batch operation.

Machine languages are the only languages understood by computers. While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. Computer programmers, therefore, use either high level programming languages or an assembly language programming. An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers. Every computer has its own unique machine language. Every program must be rewritten or recompiled, to run on different types of computers.

Input was based on punch card and paper tapes, and output was displayed on printouts. The UNIVAC and ENIAC(Electronic Numerical Integrator And Computer) computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U. S. Census Bureau in 1951. Second Generation Time Frame: Second Generation (1956-1963) Transistors replaced vacuum tubes in the second generation of computers. A transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit.

Invented in 1947 at Bell Labs, transistors later became the key component of all digital circuits, including computers. Today’s latest microprocessor contains tens of millions of microscopic transistors. Prior to the invention of transistors, the digital circuits were composed of vacuum tubes, which had many problems in operations. They were much larger, required more energy, dissipated more heat, and were more subject to failures. Without the invention of transistors, computers as we know and operate it today would not be possible.

Though the transistor was invented in 1947 it was used widespread in computers until the late 50s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. The second-generation computers l relied on punched cards for input and printouts for output. There was no significant in these areas.

But with the change from using vacuum tube to transistors significantly reduced the size of the computers. Second-generation computers operation changed from cryptic binary machine language to symbolic languages which allowed programmers to specify instructions in words. Some high-level programming languages were also being developed, such as early versions of COBOL and FORTRAN. The second generation of computers where the first computers which could store memory instructions. Third Generation Time Frame: 1964-1971 The significant development of the integrated circuit was the hallmark of the third generation of computers.

Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. At the same time bringing down the size of the computers. Silicon, a non-metallic chemical element in the carbon family of elements – atomic symbol “Si” – is the second most abundant element in the earth’s crust, surpassed only by oxygen. Sand and almost all rocks contain silicon combined with oxygen, forming silica. When silicon combines with other elements, such as iron, aluminium or potassium, a silicate is formed.

Silicon is the basic ingredient used to make computer chips, transistors, silicon diodes and other electronic circuits and switching devices because its atomic structure makes the element an ideal semiconductor. Silicon is doped, or combined with other elements, such as boron, phosphorous and arsenic, to alter its conductive properties. A chip is a small semi-conductor(usually containing silicon) on which an integrated circuit is embedded. It is less than one fourth square inches and can contain millions of electronic components (mostly transistors).

Computers consist of many chips placed on electronic boards called printed circuit boards or PCBs. For example, CPU chips (also called microprocessors) contain an entire processing unit, whereas memory chips contain blank memory. Computer chips or microprocessors, both for CPU and memory, are composed of semiconductor materials. These semiconductors make it possible to create miniature electronic components, such as transistors. Miniaturization means that the components take up less space, faster processing and require less energy.

Users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors. Fourth Generation Time Frame: 1971-Present The microprocessor hallmarked the entry into fourth generation of computers, as thousands of integrated circuits were rebuilt onto a single silicon chip.

Each silicon chip that contains a CPU.. At the heart of all personal computers and most workstations sits the microprocessor or the mother board. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles. Three basic characteristics differentiate microprocessors: •Instruction Set: The set of instructions that the microprocessor can execute. •Bandwidth: The number of bits processed in a single instruction. •Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.

The first generation computer which filled an entire room could now fit in the palm of the hand. With the development of Intel 4004chip, in 1971, located all the components of the computer – from the central processing unit and memory to input/output controls – on a single chip. The CPU is the brain of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculating and controlling take place. In terms of computing power, the CPU is the most important element of a computer system.

The three typical components of a CPU are: •The arithmetic logic unit (ALU): It performs arithmetic and logical operations. •The control unit (CU): It extracts instructions from memory and decodes and executes them, calling on the ALU when necessary. •Registers or Memory Unit: Vital to the operation of the CPU are the registers, which are very small memory locations that are responsible for holding the data that is to be processed In the year 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.

Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors. When these small computers became more powerful, they we used to be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUI’s, the mouse and handheld devices. Fifth Generation Time Frame: Present and Future The fifth generation computing devices are based on artificial intelligence though still under development, they are used widespread in areas like voice recognition.

Artificial Intelligence, coined in 1956 by John McCarthy at the Massachusetts Institute of Technology, is the branch of computer science which concerns with making computers behave like humans. It includes: •Games Playing: programming computers to play games such as chess and checkers •Expert Systems: programming computers to make decisions in real-life situations (for example, some expert systems help doctors diagnose diseases based on symptoms) •Natural Language: programming computers to understand natural human languages Neural Networks: Systems that simulate intelligence by attempting to reproduce the types of physical connections that occur in animal brains •Robotics: programming computers to see and hear and react to other sensory stimuli Presently there are no such computers which exhibit full artificial intelligence (i. e, are able to simulate human behaviour). The greatest advancements have taken place in the field of games playing. The best computer chess programs are now capable of beating humans. In May,1997, an IBM super-computer called Deep Blue defeated world chess champion Gary Kasparov in a chess match.

In the field of robotics, computers are now widely used in assembly plants, but they are capable only of very limited tasks. It faces great difficulty in identifying objects based on appearance or feel, and they still move and handle objects clumsily. There is continuous research and development in this filed to be used for other applications like defence, medicine, medical surgery etc. Today, the most talked about area of artificial intelligence is neural networks, which are proving successful in various n umber of disciplines such as voice recognition and natural-language processing.

There are several programming languages that are known as AI languages because they are used almost exclusively for AI applications. The two most common are LISP and Prolog. Introduction: Computer Hierarchy With the innovation in technology in each generation of computers, there has been development of new products. New inventions like microprocessors and transistors have helped to not only reduce the size but also the cost of the computers. The new product created in each generation of computers is briefly stated as follows: Desktop computer

Prior to the wide spread of Personal Computers a computer that could fit on a desk was considered remarkably small. Today the phrase usually indicates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. In this sense, the term ‘desktop’ refers specifically to a horizontally oriented case, usually intended to have the display screen placed on top to save space on the desk top.

Most modern desktop computers have separate screens and keyboards. Workstation A workstation is a high-end personal computer designed for applications in technical or scientific purposes. They are commonly connected to a network and run multiple operating systems. Workstations are mainly used for tasks such as design, drafting and modelling, computation-intensive scientific and engineering calculations, image processing, architectural modelling, and computer graphics for animation and motion picture visual effects. Single unit

Single unit PCs (also known as all-in-one PCs) are a subtype of desktop computers, which combine the monitor and case of the computer within a single unit. The monitor often utilizes a touchscreen as an optional method of user input, however detached keyboards and mice are normally still included. The inner components of the PC are often located directly behind the monitor, and many are built similarly to laptops. Nettop A type of desktops, called nettops, was introduced by Intel in February 2008 to describe low-cost, lean-function, desktop computers.

Similar subtypes of laptops (or notebooks) are the netbooks (see below). These feature the new Intel Atom processor which specially enables them to consume less power and to be built into small enclosures. Laptop A laptop computer or laptop, also called a notebook computer, is a personal computer designed for portability. All of the hardware needed to operate the laptop, such as USB ports , graphics card, sound channel, etc. , are built in to a single unit. Laptops contain high capacity batteries that can power the device for extensive periods of time, enhancing portability (usually 2 to 3 hours).

Once the battery charge is depleted, it will have to be recharged through a power outlet. Netbook Netbooks (also called mini notebooks or subnotebooks) are a rapidly evolving segment of small, light and inexpensive laptop computers suited for general computing and accessing web-based applications; they are often marketed as “companion devices,” that is, to augment a user’s other computer access. In the short period since their appearance, netbooks have grown in size and features, now converging with new smaller, lighter notebooks. Tablet PC A tablet PC is a slate-shaped netbook.

Its touchscreen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse. Tablet PCs are often used where normal notebooks are impractical or unwieldy, or do not provide the needed functionality. Supercomputer A supercomputer is a computer which is mostly used in the field of research and development for calculation intensive tasks. It was introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation (CDC), which led the market into the 1970s until Cray left to form his own company, Cray Research.

Today, supercomputers are typically one-of-a-kind custom designs produced by traditional companies such as Cray, IBM and Hewlett-Packard, who had purchased many of the 1980s companies to gain their experience. Currently, Japan’s K computer, built by Fujitsu in Kobe, Japan is the fastest in the world. It is three times faster than previous one to hold that title, the Tianhe-1A supercomputer located in China. Ipad The iPad is a line of tablet computers designed, developed and marketed by Apple Inc. primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content.

Its size and weight lies between those of contemporary smartphones and laptop computers. The iPad runs the operating system known as the IPhone SDK—and can run its own applications as well as iPhone applications. The iPad will only run programs approved by Apple and distributed via the Apple App Store Like iPhone and iPod Touch, the iPad is controlled by a multitouch display—a departure from most previous tablet computers, which used a pressure-triggered stylus—as well as a virtual onscreen keyboard in lieu of a physical keyboard.

The iPad uses the wireless local area network (“Wi-Fi”) connection to access local area networks and the Internet. Most of the models also have a 3G wireless network interface which can connect to HSPA or EV-DO data networks and on to the Internet. The device is managed and synced by iTunes running on a personal computer via USB cable.