CBSE Class 4 Computer Science Hardware And Software Notes

IntroductIon
The computer has two main components which define the working of computer. A computer system consists of two major elements: hardware and software.

Computer Hardware
Computer hardware is the collection of physical parts of a computer system. This includes the computer case, monitor, keyboard, and mouse. It also includes all the parts inside the computer case, such as the hard disk drive, motherboard, video card, and many others. Computer hardware is what you can physically touch.

Hardware Devices
A hardware device is a device used to put information into and get information out of the computer.
Three categories of hardware devices exist based on their relationship with the computer:
• An input device sends data or instructions to the computer, such as a mouse, keyboard, graphics tablet, image scanner, barcode reader, game controller, light pen, light gun, microphone, digital camera, webcam, dance pad, and read-only memory.
• An output device provides output from the computer, such as a computer monitor, projector, printer, and computer speaker.
• An input/output device performs both input and output functions, such as a computer data storage device (including a disk drive, USB flash drive, memory card, and tape drive) and a touch-screen.

Types of hardware devIces
1. Mouse

The mouse, sometimes called a pointer, is a hand-operated input device used to manipulate objects on a computer screen. There are different types of mouse:
• Mechanical Mouse: It has a hard rubber ball that rolls as the mouse is moved. Sensors inside the mouse body detect the movement and translate it into information that the computer interprets.
• Optical Mouse: An optical mouse is a computer pointing device that uses a light-emitting diode, an optical sensor, and digital signal processing ( DSP ).
• A trackball Mouse: A trackball mouse is a pointing device. It consists of a ball held by a socket containing sensors to detect a rotation of the ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a pointer. The operator just continues rolling with trackball but a mouse would have to be lifted and re-positioned.
• Wireless Mouse: The mouse without wire or cord is called wireless mouse or cordless mouse. Most wireless mice use radiofrequency (RF) technology to communicate information to your computer.

2. Keyboard

• The keyboard is the piece of computer hardware used to input text, characters, and other commands into a computer or similar device.
• It is flat, rectangular and usually made of plastic.
• It resembles a type-writer.
• It is an important input device.
• A keyboard is connected to the computer system using a wire or a wireless connection.

3. Motherboard

• The motherboard serves to connect all of the parts of a computer together.
• The CPU, memory, hard drives, and other ports and expansion cards all connect to the motherboard directly or via cables.

4. Scanners

Scanners are input devices that give the means to insert information into a computer. They can be used for visual information such as photographs or drawing, or teamed with typereading software to import documents and translate the hard copy to text that can be edited in word processing programs.

5. Printers

Printers provide the means for the computer to output information in portable form. Whether a document, a photograph or even an image on canvas (for more sophisticated devices), a printer allows us to reproduce information and share it with others. Some types of printers are:
• Dot Matrix Printer: These printers are the oldest established type of printers still available in the market. Images and text are drawn out in tiny dots when a print head strikes an ink-soaked cloth against the paper in the required pattern or formation.
• Inkjet Printer: These Printer are one of the most common types of printers used in both professional and domestic settings.
• The Laser Printer: It was developed by Xerox in the 1960s when the idea of using a laser to draw images onto a copier drum was first considered. Laser printers are still widely used in large offices as they are traditionally more efficient than Inkjet printers.
• LED Printers: These are similar to laser printers, but uses a Light Emitting Diode rather than a laser to create images on the print drum or belt. Due to the fewer moving parts – LED printers are often considered more efficient and reliable than laser printers.

6. Plotter

Plotter is an output device which is generally used by engineers and architects to get high quality graphical outputs of pictures and photographs.

7. Speakers 

Speaker is an output device which gives the sound output. It is used to listen to sounds and music.

8. Microphone

A microphone is an input device which is used to give sound input into the computer. It is used to record sounds and give instructions to the computer.

9. Hard disk

Hard disk is a part of the CPU and stores all the software and data of the computer.

10. Ports
A port is defined as a connection point between the computer and can be an external or internal device. Internal ports connect devices like hard drives and CD ROM or DVD drives. Whereas, external ports connect devices like modem, mouse, printers, etc.

11. PS/2 Port 
It is a 6 pin mini DIN connector and hardware interface which is used to connect mouse and keyboard to the computer. 

12. USB Cable
USB stands for Universal Serial Bus. It is the most common type of port. It is a cable connection interface which is used to connect peripheral devices to computer.

13. UPS 
It stands for Uninterruptible Power Supply. It is an electrical device which provides emergency power to the computer when the main power fails. It is used to protect the computer hardware from sudden loss of power.

Computer Software
Computer software, on the other hand, is not something you can touch. Software is a set of instructions for a computer to perform specific operations. You need both hardware and software for a computer system to work.

Types of software
Based on the function and purpose, software is broadly classified into System and Application software.

1. System Software
The system software is a collection of programs which are designed to operate, control, and extend the processing capabilities of the computer itself. This software is usually prepared by the computer manufacturers. It acts as an interface between the hardware and the user. The different types of system software are:

(i) Operating system Software

An operating system is the interface which acts between the computer hardware and the end user. 
It is system software which controls the overall activity of the computer system. Some of the commonly used operating systems are- Microsoft Windows, Mac OS X, and Linux. They are loaded when we switch on the computer.

(ii) Utility Software

Utility software is the system software which is designed to analyze, configure, manage and maintain the computer infrastructure. Utility programs provide improved functionality to the computer.
This software usually performs small tasks that fine-tunes and manages the operating system.
Examples of utility programs are antivirus software, backup software, data compression, network utilities, file managers and disk management.
• Antivirus Software: It scans the computer for possible viruses.
• Backup Software: It takes a back-up copy of data on a disk.
• Data Compression: It is used to compress the contents of the disk.
• Network Utilities: It analyses the network connectivity of computer.
• File Managers: It manages the files on the computer by performing actions like deleting, moving, merging and renaming files.
• Disk Management: It includes functions like disk cleaners, disk formatting, etc.

Application software

Application software is a group of programs designed for the end users. Thus they are also known as end user programs. This software is created for a specific purpose and performs coordinated functions and tasks for the benefits of user. Some application software commonly used are:
• Microsoft Word
• Microsoft Excel
• Student Record Software
• Railways Reservation Software
• Microsoft Presentation
• Microsoft Office Suite Software

Antivirus software

• Antivirus software, or anti-virus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware on individual computing devices, networks and IT systems.
• Antivirus software, originally designed to detect and remove viruses from computers, can also protect against a wide variety of threats, including other types of malicious software.

Antivirus software usually performs these basic functions:
• Scanning directories or specific files for known malicious patterns indicating the presence of malicious software;
• Allowing users to schedule scans so they run automatically;
• Allowing users to initiate new scans at any time; and
• Removing any malicious software it detects. Some antivirus software programs do this automatically in the background, while others notify users of infections and ask them if they want to clean the files.