Computer hardware and software concepts pdf

A CPU has 3 components as listed below. Think of the ALU as the logical part of the brain. The ALU thinks in bits i.

It is made up of a group of memory locations built directly into the CPU called registers. These are used to hold the data binary information that are being processed by the current instruction. Primary memory is memory that is part of the computer itself and necessary for its functioning. It consists of mainly two types of memories:. As soon as the machine is switched off, data is erased. RAM is volatile. Volatile means that the data stored in memory is lost when we switch off the computer or if there is a power failure.

There are different types of RAM available. Some of them are described below. The memory from which we can only read but cannot write on it. This type of memory is non-volatile. The information is stored permanently in such memories during manufacture. A ROM, stores such instructions that are required to start a computer. This operation is referred to as bootstrap.

The different types of ROM are given below. Floppy diskettes, hard disk, tapes and optical disks come under the category of external storage devices or ancillary storage devices. These devices are very sensitive to environmental conditions humidity and temperature as well as to external magnetic fields and need to be stored carefully. A scanner is used for this purpose. A scanner scans an image and transforms it into graphics. These can be edited, manipulated and combined, and then printed.

Scanners are used to reproduce photographs on the computer screen. These can be employed in training programs and in desktop publishing. Types of scanner a Flat-bed scanner or desktop scanner b Optic scanner, looks like a camera c Hand held scanner PRINTER In order to get a copy of the output for later reference, you would require a printer.

Printers are capable of printing at a very high speed. Two commonly used printers are the dot-matrix printer and the laser printer. Printers are classified on the basis of a number of parameters like, the mechanism used for printing, speed of printing, quality of output, direction of printing, and the kind of interface they have with the computer.

Printers can be broadly classified as impact and non-impact printers. Let us understand this in detail. Impact Printers Impact printers work like typewriters. The characters are printed by striking the paper i. Impact printers can again be classified as Character printers and Line printers. Character Printers Character printers print one character at a time.

Examples of character printers are. In a DMP, tiny hammers or pins strike the ribbon to produce the desired characters. The print head consists of 9x7 arrays of pins. Characters to be printed are sent one at a time to the printer.

The characters printed are a series of dots. Dot- matrix printers are inexpensive but noisy. They can print both text and graphics.

They can print in any language without additional hardware change. They can also be made to print in colour by changing ribbons. These printers are used everywhere to produce internal reports and memos needed by organizations. Daisy Wheel Printer In a daisy wheel printer, each petal has a character embossed on it. A motor spins the wheel along with it.

When the desired character spins to the correct position, a print hammer strikes it to produce a character. Line printers Line printers print one line at a time. Hence, line printers are generally faster than character printers. Printing speed varies from lines to lines per minute. Some of the line printers are drum printers and chain printers. These can continuously print for a few hours. Drum printers A drum printer consists of a cylindrical drum.

The characters to be printed are embossed on it. A set of print hammers one for each character in a line, are mounted in front of the drum. A character is printed by striking the appropriate hammer against the embossed character on the surface. The drum completes one revolution to print one line. The movement of the drum and the striking of the hammer must synchronize. Otherwise, the printing will not be uniform. As printer drums are costly they cannot be changed often.

Chain Printer A chain printer has a steel band on which the characters are embossed. The band is rotated at a high speed.

As the band rotates, a hammer is activated when the desired character comes in front of it. For every character there will be a hammer. Here also, the hammer movement and the chain movement must be synchronized. The main advantage of the chain printer is that its chain can be easily changed.

Thus, different fonts and scripts can be used with the same printer. Some examples of the non-impact are laser printer, thermal printer, and inkjet printer. Laser Printer Laser printers print one page at a time.

Laser printers use a light beam to form images on the paper using a toner ink as the medium. Laser printers are quiet workers. They produce very high quality output both text and graphics. They are typically used publishing. Other Non-impact printers The other types of non-impact printers are thermal printers which use heat to print characters on paper and inkjet printers which use jets of ink to print characters on paper.

These printers are not in use as much as the laser printers. It can be used to create presentation-charts, graphics, tables and high quality technical drawings. There are two types of plotters: Drum and Flat Bed plotter.

Drum Plotter The paper is placed over the drum that rotates back and forth. A carriage holding one or more pens is mounted horizontally across the drum. The carriage with the pens moves horizontally over the paper.

Each pen could be filled with different colours. This plotter has the ability to produce colour pictures. Flat Bed Plotter In flat bed plotter, the paper does not move. The carriage holding the pens should provide all motions. Inkjet plotters can also produce large drawings with different colours. The system unit consists of primary storage, arithmetic-logic unit, and the control unit. The CPU interprets instructions to the computer, performs the logical and arithmetic processing operations, and causes the input and output operations to occur.

It acts like the central nervous system for all the components though; it does not process any data. These separate areas are not fixed. The size of each area varies from application to application. ON state is represented by 1 and OFF state is represented by 0. A collection of 8 bits is known as a byte. One Kilobyte represents bytes and one Megabyte represents Kilobytes. Ram Random Access Memory RAM is the area that is used for holding the programs and their data while the computer is working with them.

RAM means the memory can be read from and written to randomly. These sets of programs perform the most basic control and supervisory operations for the computer. But the storage devices are not as fast as the CPU. Most of the time the CPU has to slow down because of these devices.

A small section of the high speed RAM is used to keep frequently needed information. So, one need some storage device to store data and other information. It should be cheap and should not lose the content when power is switched off. This storage is called as the secondary storage. All secondary storage devices act both as input and output devices.

Magnetic storage media fulfils these requirements and most common storage devices are disks and tapes. Floppy Disk It is the most common storage media and it helps transferring the data from one computer to another. Data is stored in these sectors. Each piece of data that is stored, has a track number, a sector number and side number as an address. So data can be accessed randomly from anywhere on the disk. Hence, it is also called as Random Access storage.

The most significant difference between a floppy disk and a hard disk is that the hard-disk is completely sealed and is protected from dust and airborne particles. The name hard disk comes from the rigid platter that is inside the drive. This is, often called by different names like fixed disk or Winchester disk.

The hard disk comes in different shapes. Most hard disks nowadays store something close to MB. Magnetic Tapes Apart from using disks for external storage purposes, magnetic tapes are also used for storing large amount data. The magnetic tape could be a large reel or a small cassette. The tape is essentially a plastic ribbon coated with some material that can be magnetized. The data is recorded on these magnetic spots. The data on the tape can however be read or written sequentially only.

Hence, it is called as sequential access storage. The computer bus consists of two parts, the address bus and a data bus. The data bus transfers actual data, whereas the address bus transfers information about where the data should go. VDUs can work in two different modes viz. Text mode and graphic mode. In text mode, the screen is divided into a matrix of rows and columns; each cell of the matrix is used for one character. A typical screen has 80 character positions per line and 25 lines across the screen.

In graphic mode, the screen is treated as an array of tiny dots called pixels. The characters and pictures that appear on the screen are shown by making a drawing of these pixels.

The number of dots on the screen is called as resolution. The higher the resolution the better the picture. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning.

The acquisition of 21st century competencies of communication, critical and creative thinking and the ability to locate, understand and reflect on various kinds of information has become more crucial for our learners. It is well accepted that Reading Literacy is not In view of the current Hence, there is a need that all the students appearing in the Term-l examinations and the schools sponsoring these students should have NCERT now offers online courses for This festival showcases the Main types of software — systems software and application software.

Application software Application software — a computer program that provides users with tools to accomplish a specific task. Examples of application software: word processing, spreadsheets, presentation, database management, Internet browsers, email programs, media players, accounting, pronunciation, translation, desktop publishing, enterprise, etc. It serves as the interface between hardware, application software, and the user.