The Computer


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The Patient Medical Record as a Database. An Algorithm for Constructing University Timetables. An efficient method for finding the minimum of a function of several variables without calculating derivatives. Function minimization by conjugate gradients.


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A new approach to variable metric algorithms. Related Titles. Interacting with Computers. Journal of Logic and Computation. Journal of Complex Networks. Considered the " father of the computer ", [17] he conceptualized and invented the first mechanical computer in the early 19th century.

First mechanical computer or automatic computing engine concept

After working on his revolutionary difference engine , designed to aid in navigational calculations, in he realized that a much more general design, an Analytical Engine , was possible. The input of programs and data was to be provided to the machine via punched cards , a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later.

The Engine incorporated an arithmetic logic unit , control flow in the form of conditional branching and loops , and integrated memory , making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete. The machine was about a century ahead of its time.

Eventually, the project was dissolved with the decision of the British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to political and financial difficulties as well as his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow.

When was the first computer invented?

Nevertheless, his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit the mill in He gave a successful demonstration of its use in computing tables in During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers , which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers. The differential analyser , a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in by James Thomson , the brother of the more famous Lord Kelvin.

The art of mechanical analog computing reached its zenith with the differential analyzer , built by H. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. A dozen of these devices were built before their obsolescence became obvious. By the s, the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remained in use during the s in some specialized applications such as education control systems and aircraft slide rule. By , the United States Navy had developed an electromechanical analog computer small enough to use aboard a submarine.

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This was the Torpedo Data Computer , which used trigonometry to solve the problem of firing a torpedo at a moving target. During World War II similar devices were developed in other countries as well. Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2 , created by German engineer Konrad Zuse in , was one of the earliest examples of an electromechanical relay computer.

In , Zuse followed his earlier machine up with the Z3 , the world's first working electromechanical programmable , fully automatic digital computer. It was quite similar to modern machines in some respects, pioneering numerous advances such as floating point numbers. Rather than the harder-to-implement decimal system used in Charles Babbage 's earlier design , using a binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time.

Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers , working at the Post Office Research Station in London in the s, began to explore the possible use of electronics for the telephone exchange.

Experimental equipment that he built in went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. The German encryption machine, Enigma , was first attacked with the help of the electro-mechanical bombes which were often run by women. Colossus was the world's first electronic digital programmable computer.


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  5. It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data, but it was not Turing-complete. Colossus Mark I contained 1, thermionic valves tubes , but Mark II with 2, valves, was both 5 times faster and simpler to operate than Mark I, greatly speeding the decoding process.

    Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches. It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract times a second, a thousand times faster than any other machine.

    It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words about 80 bytes. Built under the direction of John Mauchly and J. The machine was huge, weighing 30 tons, using kilowatts of electric power and contained over 18, vacuum tubes, 1, relays, and hundreds of thousands of resistors, capacitors, and inductors. The principle of the modern computer was proposed by Alan Turing in his seminal paper, [41] On Computable Numbers.

    Turing proposed a simple device that he called "Universal Computing machine" and that is now known as a universal Turing machine. He proved that such a machine is capable of computing anything that is computable by executing instructions program stored on tape, allowing the machine to be programmable. The fundamental concept of Turing's design is the stored program , where all the instructions for computing are stored in memory.

    Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete , which is to say, they have algorithm execution capability equivalent to a universal Turing machine.

    Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine. A stored-program computer includes by design an instruction set and can store in memory a set of instructions a program that details the computation. The theoretical basis for the stored-program computer was laid by Alan Turing in his paper. In , Turing joined the National Physical Laboratory and began work on developing an electronic stored-program digital computer. His report "Proposed Electronic Calculator" was the first specification for such a device.

    The Manchester Baby was the world's first stored-program computer. Grace Hopper was the first person to develop a compiler for programming language. The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1 , the world's first commercially available general-purpose computer. At least seven of these later machines were delivered between and , one of them to Shell labs in Amsterdam. The LEO I computer became operational in April [48] and ran the world's first regular routine office computer job.

    The bipolar transistor was invented in From onwards transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life.

    Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space. At the University of Manchester , a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. The next great advance in computing power came with the advent of the integrated circuit. The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence , Geoffrey W.

    Produced at Fairchild Semiconductor, it was made of silicon , whereas Kilby's chip was made of germanium.

    When was the first computer invented?

    This new development heralded an explosion in the commercial and personal use of computers and led to the invention of the microprocessor. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel , [58] designed and realized by Ted Hoff , Federico Faggin , and Stanley Mazor at Intel.

    System on a Chip SoCs are complete computers on a microchip or chip the size of a coin. If not integrated, The RAM is usually placed directly above known as Package on package or below on the opposite side of the circuit board the SoC, and the flash memory is usually placed right next to the SoC, this all done to improve data transfer speeds, as the data signals don't have to travel long distances.

    Since ENIAC in , computers have advanced enormously, with modern SoCs being the size of a coin while also being hundreds of thousands of times more powerful than ENIAC, integrating billions of transistors, and consuming only a few watts of power. The first mobile computers were heavy and ran from mains power. The 50lb IBM was an early example. Later portables such as the Osborne 1 and Compaq Portable were considerably lighter but still needed to be plugged in.

    The first laptops , such as the Grid Compass , removed this requirement by incorporating batteries — and with the continued miniaturization of computing resources and advancements in portable battery life, portable computers grew in popularity in the s. These smartphones and tablets run on a variety of operating systems and recently became the dominant computing device on the market, with manufacturers reporting having shipped an estimated million [ clarification needed ] devices in 2Q The term hardware covers all of those parts of a computer that are tangible physical objects.

    Circuits, computer chips, graphic cards, sound cards, memory RAM , motherboard, displays, power supplies, cables, keyboards, printers and "mice" input devices are all hardware. These parts are interconnected by buses , often made of groups of wires. Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit binary digit of information so that when the circuit is on it represents a "1", and when off it represents a "0" in positive logic representation.

    The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits. When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are:. The means through which computer gives output are known as output devices.

    Some examples of output devices are:. The control unit often called a control system or central controller manages the computer's various components; it reads and interprets decodes the program instructions, transforming them into control signals that activate other parts of the computer. A key component common to all CPUs is the program counter , a special memory cell a register that keeps track of which location in memory the next instruction is to be read from. The control system's function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:.

    Since the program counter is conceptually just another set of memory cells, it can be changed by calculations done in the ALU. Adding to the program counter would cause the next instruction to be read from a place locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops instructions that are repeated by the computer and often conditional instruction execution both examples of control flow.

    The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program, and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer , which runs a microcode program that causes all of these events to happen. Early CPUs were composed of many separate components but since the mids CPUs have typically been constructed on a single integrated circuit called a microprocessor. The ALU is capable of performing two classes of operations: arithmetic and logic. Some can only operate on whole numbers integers while others use floating point to represent real numbers , albeit with limited precision.

    However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values true or false depending on whether one is equal to, greater than or less than the other "is 64 greater than 65?

    These can be useful for creating complicated conditional statements and processing boolean logic. Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously. A computer's memory can be viewed as a list of cells into which numbers can be placed or read.

    Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number into the cell numbered " or to "add the number that is in cell to the number that is in cell and put the answer into cell Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers.

    In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits called a byte. To store larger numbers, several consecutive bytes may be used typically, two, four or eight. When negative numbers are required, they are usually stored in two's complement notation.

    Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory.

    The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory which is often slow compared to the ALU and control units greatly increases the computer's speed. ROM is typically used to store the computer's initial start-up instructions.

    In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In embedded computers , which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware , because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable.

    It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary. In more sophisticated computers there may be one or more RAM cache memories , which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

    Hard disk drives , floppy disk drives and optical disc drives serve as both input and output devices. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics. A era flat screen display contains its own computer circuitry. While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously.

    This is achieved by multitasking i. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time". Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant.


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    This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn. Before the era of inexpensive computers, the principal use for multitasking was to allow many people to share the same computer. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred.

    This frees up time for other programs to execute so that many programs may be run simultaneously without unacceptable speed loss. Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed only in large and powerful machines such as supercomputers , mainframe computers and servers.

    Multiprocessor and multi-core multiple CPUs on a single integrated circuit personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result. Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation , graphics rendering , and cryptography applications, as well as with other so-called " embarrassingly parallel " tasks.

    Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. Software is that part of a computer system that consists of encoded information or computer instructions, in contrast to the physical hardware from which the system is built.

    Computer software includes computer programs , libraries and related non-executable data , such as online documentation or digital media. It is often divided into system software and application software Computer hardware and software require each other and neither can be realistically used on its own. There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications. The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed.

    That is to say that some type of instructions the program can be given to the computer, and it will process them. Modern computers based on the von Neumann architecture often have machine code in the form of an imperative programming language. In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second gigaflops and rarely makes a mistake over many years of operation.

    Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors. This section applies to most common RAM machine —based computers. In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out executed in the order they were given.

    However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions or branches. Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event.

    Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to the instruction following that jump instruction. Program execution might be likened to reading a book. Whether they're on our desktops, in our homes, our pockets or just about anywhere else. In this series, you're gonna learn how computers really work. Starting with what makes a computer a computer.

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    Then, you'll look at how information is represented inside the computer using tiny electrical signals going on and off at mind-boggling speeds. After that, you'll learn how computers choose circuits to do everything from simple math to simulating entire virtual worlds.

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