Definition of Computer

Computer is th programmable machine that can store, retrieve, and process data. Today's computers have at least one CPU that performs most calculations and includes a main memory, a control unit, and an arithmetic logic unit. Acomputer is distinguished from a calculating machine, such as an electronic calculator, by being able to store a program by the number and complexity of the operations it can perform, and by its ability to process, store, and retrieve data without human intervention.There are 2 types of computer production. These are:A>Analog Computers

B>Digital Computers

A>Analog Computers

An analog computer represents data as physical quantities and operates on the data by manipulating the quantities. It is designed to process data in which the variable quantities.The key component of the analog computer is the operational amplifier and the computer's capacity is determined by the number of amplifiers it contains.

B>Digital Computers

A digital computer is designed to process data in numerical form. its circuits perform directly the mathematical operations of addition, subtraction, multiplication, and division.Digital computers are used for reservations systems, scientific investigation, data-processing and word-processing applications, desktop publishing, electronic game, and many other purposes.

Development of Computers

Although the development of digital computers is rooted in the abacus and early mechanical calculating devices, Charles Babbage is credited with the design of the first modern computer, the "analytical engine," during the 1830s. American scientist Vannevar Bush built a mechanically operated device, called a differential analyzer, in 1930; it was the first general-purpose analog computer. John Atanassoff constructed the first semielectronic digital computing device in 1939.

First-generation computers were supplanted by the transistorized computers of the late 1950s and early 60s, second-generation machines that were smaller, used less power, and could perform a million operations per second. They, in turn, were replaced by the third-generation integrated-circuit machines of the mid-1960s and 1970s that were even smaller and were far more reliable. The 1980s and 90s were characterized by the development of the microprocessor and the evolution of increasingly smaller but powerful computers, such as the personal computer and personal digital assistant, which ushered in a period of rapid growth in the computer industry.

Functions of Computer

• A> Control Unit
• B> Arithmetic and Logical Unit(ALU)
• C> Memory
• D> Input/Output
• E> Multitasking
• F> Multiprocessing
• G> Networking and Internet

Control Unit

The control unit manages the computer's various components; it reads and decodesIt is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program the program instructions, transforming them into a series of control signals which activate other parts of the computer.

Arithmetic/Logical Unit(ALU)

The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing. Computers may contain multiple ALUs so that they can process several instructions at the same time.

Memory

A computer's memory can be viewed as a list of cells into which numbers can be placed.The information stored in memory may represent practically anything.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. Computer main memory comes in two principal varieties: Random Access Memory(RAM) and Read Only Memory(ROM).RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it.ROM is typically used to store the computer's initial start-up instructions.

Input/Output

Devices that provide input or output to the computer are called peripherals.I/O devices are complex computers in their own right with their own CPU and memory.

Multitasking

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.e. having the computer switch rapidly between running each program in turn. Multitasking would cause a computer that is switching between several programs to run more slowly in direct proportion to the number of programs it is running.

Multiprocessing

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 Super Computers, Mainframe Computers and servers. Multiprocessor and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.

Networking and Internet

Computers have been used to coordinate information between multiple locations since the 1950s.In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology.