We find computers around the
house, in schools, hospitals, railway stations, airports, banks and shopping
malls and so on. Before proceeding with our study of computers, let us first
define a computer. A computer is an electronic machine that takes input, processes
it to produce the desired output. Each computer is a combination of hardware
and software. The physical components of a computer that can be seen and
touched make the hardware. For example, CPUs, monitors, keyboards, printers,
etc., are hardware or peripheral devices. Input instructions are given to the
computer. This set of instructions that we give to a computer to perform a
specific task forms a program. Many such programs work together to create
software for a computer. Operating system, antivirus, MS Office fees, computer
games are all software software applications.
Components of a Computer
(1) Input Devices: These are
the devices that are used to accept user data and instructions. Keyboard,
mouse, scanner, etc., are examples of input devices.
(2) Central Processing Unit
(CPU): This computer is known as the 'brain of the computer' as it controls the
entire operation of the computer.
(3) Memory: Data and
instructions are stored in this component of the computer. Hard disks, DVDs,
pen drives, etc. are examples of memory storage devices.
(4) Output Devices: These are
the devices that are used to display the desired result or information.
Monitors, printers, etc., are examples of output devices.
Arithmetic Logic Unit (ALU)
The arithmetic logic unit or ALU performs
two types of operations - arithmetic and logical. Arithmetic operations are
basic mathematical operations that include addition, subtraction,
multiplication and migration operations. Logical operations operations have boolean
comparisons such as AND, OR and no.
Monitor
The monitor is similar to a
television screen and is used to display data and information. When some data
or notification key is held, the monitor displays the typing characters.
Monitors are available in a variety of sizes. They may also be different for
different types of computers. The standard size is 80 characters by 24
characters. The output displayed on the monitor is known as software. There are
two types of monitors - CRT and TFT-LCD monitors
Plotter
A plotter is a device used to draw charts,
graphs, maps, etc., with two or more automatic pens. Multi-colored plotters use
different colored pens to create multi-colored output. There are different
types of plotters available in the market. A paper is wrapped around the
rotating drum near the drum plotter and the pen proceeds on the paper to print
the output. The flatbed plot has a flat surface on which the paper is placed
and the pen proceeds to draw the output. The electrostatic plot consists of
negatively charged paper on which a drawing is made using positively charged
toner. Plotters are more expensive than printers. These were the first devices
that could print full-size engineering drawings with color. They are frequently
used for computer aided engineering (CAE) applications such as computer aided
design (CAD) and computer aided manufacturing (CAM).
Memory Unit
There are 2 types of computer inbuilt memory: primary and secondary. Primary memory can be accessed directly through the central processing unit. RAM is an example of primary memory. You will learn more about RAM later in this lesson. As soon as the computer is turned off, the primary memory loses its contents. But data can be stored and retrieved at a much faster rate with primary memory than with secondary memory. Examples of secondary memory storage devices are floppy disks, magnetic disks, hard disks, CDs, pen drives, etc. Secondary memory devices can be located inside or inside a computer. Primary memory is more expensive than secondary memory. When the computer is performing any task, the information that needs to be processed is stored in the primary memory. This data may come from an input device such as a keyboard or from a secondary storage device such as a hard disk. Since the program or set of instructions is kept in primary memory, the computer is able to follow it immediately. For example, when you book a ticket from a railway reservation counter, follow a few steps to the computer, such as, request, check the availability of seats, calculate the fare, wait for payment, save the reservation and print the ticket. A program containing these steps is kept in the computer's primary memory. But inside the computer, the steps followed are quite different from what appears on the monitor or screen. Both programs and data are stored in binary form in the computer's memory. You are already presented with a decimal number system which is a number from 0 to 9. The binary systems contains only two digits, 0 & 1.
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