Some history of computinghttp://en.wikipedia.org/wiki/History_of_computing_hardware

ComputerA machine that can be programmed to manipulate symbols. Computers can perform complex and repetitive procedures quickly, precisely and reliably and can quickly store and retrieve large amounts of data. The physical components from which a computer is constructed (electronic circuits and input/output devices) are known as "hardware". Most computers have four types of hardware component: CPU, input, output and memory. The CPU (central processing unit) executes programs ("software") which tell the computer what to do. Input and output (I/O) devices allow the computer to communicate with the user and the outside world. There are several kinds of memory - fast, expensive, short term memory (e.g. RAM) to hold intermediate results, and slower, cheaper, long-term memory (e.g. magnetic disk and magnetic tape) to hold programs and data between jobs.

Earliest hardware

Devices have been used to aid computationThe Roman abacus was used in Babylonia as early as 2400 BCA number of analog computers were constructed in ancient and medieval times to perform astronomical calculationsThe Antikythera mechanism and the astrolabe from ancient Greece (c. 150100 BC) The astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer

First Generation (1940-1956) have started in 1946 with ENIAC, the first 'computer' to use vacuum tubesthere was no 'best' way of storing instructions and data in a computer memory > used magnetic drums as their main memoryProgrammed in machine language, the lowest-level programming language understood by computersExamples of first-generation computing devices: UNIVAC (1951 business) and ENIAC (1946 US army).

Second Generation (1956-1963)Transistors (invented in 1947) replaced vacuum tubes and ushered in the second generation of computersProgrammed in assembly language (allowed programmers to specify instructions of the machine language in words)High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN.The first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

Third Generation (1964-1971) Transistors were miniaturized and placed on silicon chips > integrated circuit (increased the speed and efficiency)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

Fourth Generation (1971-Present) Thousands of integrated circuits were built onto a single silicon chip > microprocessorThe Intel 4004 chip, developed in 1971, located all the components of the computer, from the central processing unit and memory to input/output controls, on a single chip. Small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet.

Fifth Generation (Present and more then Beyond)Based on artificial intelligenceUse of parallel processing and superconductors are helping to make artificial intelligence a realityUse of devices that respond to natural language input and are capable of learning and self-organization.

Konrad Zuse (1910, Berlin 1995, Hfeld) First functional program-controlled Turing-complete computer Z3;First high-level programming language, Plankalkl, first published in 1948;The earliest computer businesses, in 1946 (the Z4 became the second commercial computer leased to ETH Zrich in 1950)

John von Neumann (1903, Budapest 1957, Washington DC)Ph.D. in mathematics (with minors in experimental physics and chemistry) from the University of Budapest at the age of 23.In 1937 he became a naturalized citizen of the US. described a computer architecture in which data and program memory are mapped into the same address space

Alan Turing (1912, London 1954, Wilmslow )Often considered to be the father of modern computer science Designed an electromechanical machine which could help break Enigma He introduced an abstract computing machine in 1936, called the Turing machine, to give a mathematically precise definition of computability

Seymour Cray (1925, Chippewa Falls - 1996, Colorado Springs)Supercomputers introduced in the 1960s were designed primarily by Seymour Cray at Control Data Corporation (CDC) ;The speed of a supercomputer is generally measured in "FLOPS" (FLoating Point Operations Per Second), design of his own massively parallel machine

Some critical terms

Central Processing UnitCPU or processor - the part of a computer which controls all the other partsThe CPU fetches instructions from memory and decodes them. This may cause it to transfer data to or from memory or to activate peripherals to perform input or outputA parallel computer has several CPUs which may share other resources such as memory and peripherals.

Main MemoryThe storage device used by a computer to hold the currently executing program and its working dataA modern computer's main memory is built from Random Access Memory integrated circuits.Computers have several other sorts of memory, distinguished by their access time, storage capacity, cost, and the typical lifetime or rate of change of the data they hold (cache, PROM, magnetic disk - which may be used for virtual memory and magnetic tape).

Programming LanguageA formal language in which computer programs are writtenThe definition of a particular language consists of both syntax (how the various symbols of the language may be combined) and semantics (the meaning of the language constructs).Languages are classified as low level if they are close to machine code and high level if each language statement corresponds to many machine code instructions

Operating SystemThe low-level software which schedules tasks, allocates storage, handles the interface to peripheral hardware and presents a default interface to the user when no application program is runningThe OS may be split into a kernel which is always present and various system programs which use facilities provided by the kernel to perform higher-level house-keeping tasks, often acting as servers in a client-server relationship.