COMPONENTS OF A COMPUTER

There many components of a computer let us know from the basics

COMPUTER HARDWARE

Computer hardware consists of input devices, output devices, circuitry, memory, and the central processing unit (CPU) where processing and operations are performed. Input devices, such as a keyboard or mouse, are the means by which the computer takes in symbolic data and instructions. Output devices, such as the monitor or printer, are the means by which the computer sends out the symbolic results.

The CPU is the brain that controls the rest of the hardware. It is made up of three different parts: the processor, arithmetic logic unit (ALU) and internal memory. The processing unit or processor controls all the other parts of the computer. It accepts input and stores it in the memory and it interprets the instructions in a computer program. The arithmetic logic unit (ALU) performs various operations, such as addition, subtraction, multiplication, division, as well as others. The processor and the ALU use a small amount of the internal memory; most data are stored in external memory devices using hard or floppy disk drives that are attached to the processor.

COMPUTER SOFTWARE

Computer software is defined as the programs that control the computer system. Software includes the operating system, system utilities, computer languages, and computer applications.

Computer design is based on devices with two states (open or closed circuits, on or off switches). The storage cells in the main memory are groups of electronic circuits, each of which is turned on (current flowing through it) or turned off (no current flowing through it). All the data and instructions stored in the computer are represented by strings of these "on" and "off" switches. Machine language is the language understood by the computer and is closely tied to the design of the computer. A bit, the smallest unit of storage in a computer, represents each "on" or "off" circuit. The smallest group of bits commonly addressed by present day CPU's is made up of eight bits, and is referred to as a byte. Because of this two state technology, machine language is written using two symbols, usually the digits 0 and 1. Therefore, machine language is also referred to as a binary language.

These strings of binary digits are very difficult for a human to decipher so a more compact form has been devised in which each group of three binary digits was replaced by a single number in the range 0-7 (octal digits). Machine language, which is a low-level language, may be different for various types of computers. Thus, the binary (base 2) sequence 010100011 010 000 010111 would be replaced by the octal (base 8) sequence 243 2 0 27.

A further development is the use of names to identify memory locations. These assembly languages use terms such as ADD (instead of the binary code 1101) and MOVE.L (A3),D0 (instead of the binary code 0010000000010011). An assembler translates the assembly language program into the machine language. But the language is still difficult and because it is specific to particular computers, the same assembly language program can not be run on different types of computers.

Computer software also includes software tools (editors, word processors, spreadsheet programs, and database management programs) and operating systems. An operating system is a set of programs that control the operation of the hardware of a computer and application programs submitted by users.

Types of Computers Computers come in a variety of types designed for different purposes, with different capabilities and costs. Microcomputers A microcomputer is a computer that has a microprocessor chip as its CPU. They are often called personal computers because they are designed to be used by one person at a time. Personal computers are typically used at home, at school, or at a business. Popular uses for microcomputers include word processing, surfing the web, sending and receiving e-mail, spreadsheet calculations, database management, editing photographs, creating graphics, and playing music or games. Personal computers come in two major varieties, desktop computers and laptop computers:
Desktop computers are larger and not meant to be portable. They usually sit in one place on a desk or table and are plugged into a wall outlet for power. The case of the computer holds the motherboard, drives, power supply, and expansion cards. This case may lay flat on the desk, or it may be a tower that stands vertically (on the desk or under it). The computer usually has a separate monitor (either a CRT or LCD) although some designs have a display built into the case. A separate keyboard and mouse allow the user to input data and commands.
Laptop or notebook computers are small and lightweight enough to be carried around with the user. They run on battery power, but can also be plugged into a wall outlet. They typically have a built-in LCD display that folds down to protect the display when the computer is carried around. They also feature a built-in keyboard and some kind of built-in pointing device (such as a touch pad). While some laptops are less powerful than typical desktop machines, this is not true in all cases. Laptops, however, cost more than desktop units of equivalent processing power because the smaller components needed to build laptops are more expensiv e. Personal Digital Assistant and Palmtop Computers
A Personal Digital Assistant (PDA) is a handheld microcomputer that trades off power for small size and greater portability. They typically use a touch-sensitive LCD screen for both output and input (the user draws characters and presses icons on the screen with a stylus). PDAs communicate with desktop computers and with each other either by cable connection, infrared (IR) beam, or radio waves. PDAs are normally used to keep track of appointment calendars, to-do lists, address books, and for taking notes. A Palmtop or handheld PC is a very small microcomputer that also sacrifices power for small size and portability. These devices typically look more like a tiny laptop than a PDA, with a flip-up screen and small keyboard. They may use Windows CE or similar operating system for handheld devices. Some PDAs and palmtops contain wireless networking or cell phone devices so that users can check e-mail or surf the web on the move. Workstations/Servers
A workstation is a powerful, high-end microcomputer. They contain one or more microprocessor CPUs. They may be used by a single-user for applications requiring more power than a typical PC (rendering complex graphics, or performing intensive scientific calculations). Alternat ely, workstation-class microcomputers may be used as server computers that supply files to client computers over a network. This class of powerful microcomputers can also be used to handle the processing for many users simultaneously who are connected via terminals; in this respect, high-end workstations have essentially supplanted the role of minicomputers (see below). Note: The term “workstation” also has an alternate meaning: In networking, any client computer connected to the network that accesses server resources may be called a workstation. Such a network client workstation could be a personal computer or even a “workstation” as defined at the top of this section. Note: Dumb terminals are not considered to be network workstations (client workstations on the network are capable of running programs independently of the server, but a terminal is not capable of independent processing). There are classes of computers that are not microcomputers. These include supercomputers, mainframes, and minicomputers. Minicomputers
A minicomputer is a multi-user computer that is less powerful than a mainframe. This class of computers became available in the 1960’s when large scale integrated circuits made it possible to build a computer much cheaper than the then existing mainframes (minicomputers cost around $100,000 instead of the $1,000,000 cost of a mainframe). The niche previously filled by the minicomputer has been largely taken over by high-end microcomputer workstations serving multiple users (see above). Mainframes
A mainframe computer is a large, powerful computer that handles the processing for many users simultaneously (up to several hundred users). The name mainframe originated after minicomputers appeared in the 1960’s to distinguish the larger systems from the smaller minicomputers. Users connect to the mainframe using terminals and submit their tasks for processing by the mainframe. A terminal is a device that has a screen and keyboard for input and output, but it does not do its own processing (they are also called dumb terminals since they can’t process data on their own). The processing power of the mainframe is time-shared between all of the users. (Note that a personal computer may be used to “emulate” a dumb terminal to connect to a mainframe or minicomputer; you run a program on the PC that pretends to be a dumb terminal). Mainframes typically cost several hundred thousand dollars. They are used in situations where a company wants the processing power and information storage in a centralized location. Mainframes are also now being used as high-capacity server computers for networks with many client workstations. Supercomputers
A supercomputer is mainframe computer that has been optimized for speed and processing power. The most famous series of supercomputers were designed by the company founded and named after Seymour Cray. The Cray-1 was built in the 1976 and installed at Los Alamos National Laboratory. Supercomputers are used for extremely calculation-intensive tasks such simulating nuclear bomb detonations, aerodynamic flows, and global weather patterns. A supercomputer typically costs several million dollars. Recently, some supercomputers have been constructed by connecting together large numbers of individual processing units (in some cases, these processing units are standard