Explain the Computer ‘Hardware details and basic requirements for computers
Hardware is the term given to the physical components of the computer system and various individual pieces of equipment. Thus the key board, monitor, mouse, printers etc., all come under the category of hardware. Therefore, different parts of a computer can be termed as hardware. The functions of hardware are :
- to accept and store the input data in the system.
- To process the data accepted by the system.
- To give the processed results as output to the user.
Parts of a computer : The parts of the computer can be grouped into Input devices, the Processor and the Output devices.
a) Input devices : Key board, mouse, joystick, scanner, bar code reader etc. are called input devices. Data and instructions need to be entered into the memory of the computer to perform various tasks. . The input devices enable the users to input the data into the system which is processed in the processor and delivers the output.
b) Output devices : These are the devices through which the computer can provide the results to the user. Printers, Monitor etc. are output devices.
c) Central Processing unit (CPU) : All the computing in a computer is done by the Central Processing Unit and the Main Memory of the computer. This is the brain of the computer. The input from the input devices is fed into the CPU for processing. The CPU uses software to process this input and sends the output to the output devices. CPU consists of two parts viz.,
(i) Arithmetic and Logic Unit (ALU) and
(ii) Control Unit
Arithmetic and Logic Unit (ALU) : It is the part of the CPU that does all the arithmetic and logical operations like addition, subtraction, multiplication, division operations such as X > Y etc.
Control unit : It coordinates all the operations of the computer. It controls the input and output devices, the ALU and the memory. It also ensures that instructions in the software are carried out.
Memory Storage : The memory storage is of two types.
(1) Primary Memory and (2) Secondary Memory.
Primary Memory : This is the main memory of the computer and is linked to the CPU and is part of the base unit. RAM and ROM are different divisions of the primary memory.
a) Read Only Memory (ROM) : This is meant for information that is permanently required to run the computer and will remain, even if the computer is switched off. This is important because it contains all the information that the computer requires to start up.
b) Random Access Memory (RAM) : This is used for temporary storage. All the data and programs required for running a process are stored here, until the process is over. More RAM storage space can make the computer work faster. All the data o the RAM is lost when the power is turned off.
Secondary Memory : All the data and programmes which are not running on the CPU are stored in the secondary memory. They are copied into the RAM whenever they are required. The commonly used secondary memory storage devices are disks and tapes. There are three types of disks- Hard Disk, Floppy Disk and Compact Disk. Hard disks are fitted into the computer whereas the floppy disks, compact disks can be taken out and kept outside. A floppy can hold only 1.44 MB of information whereas compact disks can hold about 600 MB of data. The floppy drive is referred to as 'A' drive. If there is a second floppy drive on the computer it is referred to as 'B' drive and the hard disk is termed as 'C' drive. The alphabets D,E, F etc., are reserved for additional hard drives that the computer may have.
Some storage devices :
1. Floppy disk – 3 ½ inch diameter (previously we had 5 ¼ inch floppy disks also) : It is divided into concentric circles called tracks and the tracks are further divided into sectors. There is a small hole on the disk called index hole which denotes the starting point of the first sector. The 3 ½ inch floppy disks can store 1.44 MB or 2.88 MB of information.
2. Hard Disk : The disk consists of a disk pack containing hard disks/platters stacked onto one another. A single hard disk is made of metal and coated on both sides with metallic oxide. Hard disks can store large volumes of data as compared to floppy disks. Today we can see hard disks of capacity of 40 GB to 200 GB and even more. Portable (external) hard disks are also available now.
3. Digital Audio Tape (DAT) : This is widely used in our Bank for taking backups particularly in Bankmaster branches. It looks like an audio cassette and can store large volume of data ranging from 2 GB to 20 GB and even more.
4. CD ROM : These are also widely used now-a-days for data storage, storing music, video (cinemas) etc. Compact Disk (CD) can store up to 700 MB of data on it. Rewritable CDs are also available. This is a form of optical storage.
5. DVD (Digital Versatile Disk) : DVDs also look like CDs but can store much more data than that in CD. They can store 4.7 GB data on it. Dual layer DVDs can store almost double the data that can be stored on a normal DVD (single layer) i.e., up to 8.5 GB. Data recording is accomplished by burning the laser beam on CDs and DVDs.
6. Pen Drives / Flash Drives : These are also storage media ranging from 256 MB to 8 GB and more. These are very small and portable and easy to carry volume of data.
