I. INPUT DEVICES:
An input device is a hardware or peripheral device takes data and instructions from us and converts them into binary form that the computer can understand. Some of the devices which are used to enter data into the computer are as follows:
1. Keyboard:
A computer keyboard is an input device that allows a person to enter letters, numbers, and other symbols. Using a keyboard to enter lots of data is called typing. A keyboard can be connected to the computer through a wire or through a wireless connection.
2. Mouse:
A computer mouse is a handheld hardware input device that controls a cursor in a GUI (graphical user interface) and can move and select text, icons, files, and folders on your computer. A mouse can be a ball mouse, an optical mouse or a wireless mouse.
The ball mouse has a small metal or rubber ball under it. The movement of the mouse causes the ball to move.
The optical mouse uses light beam or light-emitting diode (LED) to detect the motion of the mouse.
A wireless mouse is not attached to the computer through a wire. Instead, the mouse uses some manner of wireless technology, like Bluetooth, infrared radio waves. Usually, a USB receiver is plugged into the computer and receives signals from the wireless mouse. A wireless mouse is more expensive than an optical or a ball mouse.
3. Scanner:
A scanner is a device that is used for creating a digital copy of the printed images or documents. The digital copy can be edited, sent as attachments through emails or saved. There are various types of scanners such as flatbed scanners, sheet-fed scanners, Drum scanners and handheld scanners. The most commonly used is the flatbed scanner.
4. Joystick:
A joystick is a cursor control device that is used to change the position of the cursor or any object on the screen. joysticks are popularly used for playing video games.
5. Light Pen:
A light pen is an input device and is shaped like a pen. It allows the user to point to displayed objects or draw on the screen in a similar way to a touchscreen but with greater positional accuracy.
6. Microphone:
A microphone is used to input sound into a computer. It helps in recording your voice or other sounds.
7. Graphic Tablet:
A graphic tablet is an input device. It is used to draw images and pictures on the computer screen and capturing the handwritten signatures of people in a similar way as you draw pictures with a pencil on paper. A graphic tablet consists of a flat surface on which a user can draw using a pen-like drawing device called stylus.
8. Barcode Reader:
A barcode is device used to capture and read information contained in a barcode. A barcode is a small image of lines and spaces that can be seen on the packets of many products. Barcodes are widely used in supermarkets for recording the sale of items quickly.
9. Touch Screen:
A touch screen is a touch-sensitive computer display screen that can also act as an input device.Touch screens are easy to use, and are often found in public places such as cell phones, ATM machines, video games and airports.
10. MICR:
MICR stands for Magnetic Ink Character Recognition. An MICR reader is a device used mainly by the banking industry to ease the processing and clearance of cheques and other documents. The MICR line on a cheque contains details such as the branch code and cheque number. They are printed at the bottom using a special magnetic ink.
11. OCR:
OCR stands for Optical Character Recognition. OCR is an input device used to read a printed text. OCR scans the text optically, character by character, converts them into a machine readable code, and stores the text on the system memory.
12. OMR:
OMR stands for Optical Mark Recognition. OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice questions.
II. OUTPUT DEVICES:
An output device takes data in the binary form from the computer and converts it into a form that we can read i.e user-readable form. Some of the devices which are used to display the processed result or output are as follows:
1. Monitor:
A computer monitor is an output device that displays information in pictorial form. It is also known as VDU (Visual Display Unit). The picture on a monitor is made up of thousands of tiny colored dots called pixels or picture elements. The quality and details of a picture depend on the number of pixels that the monitor can display. The higher number of pixels, the better is the quality of the output. There can two types of monitors-
- CRT (Cathode Ray Tube): CRT is the old style monitors that are bulky and heavy.
- TFT (Thin Film Transistor): TFT is a liquid crystal display (LCD) technology. All LCD color display such as televisions use TFT technology. TFT monitors are thin and lightweight.
2. Printer:
Printers are output devices which are used to prepare permanent output on paper. The output of the printer taken on paper is known as hard copy. There can two types of Printers
Impact Printers: An impact printer is a class of printers that functions by making physical contact with an ink ribbon before striking the page.
Examples: Daisy wheel, dot matrix and line printers
Non-impact printer: Non-impact printer prints without making contact with the paper. They are generally quieter and more efficient than their impact counterparts.
Examples: Laser printer and Inkjet printers
3. Plotter:
A plotter is a special output device used to produce hard copies of large graphs and designs on paper, such as construction maps, engineering drawings, architectural plans and business charts.
4. Speaker:
A computer speaker is an output hardware device that connects to a computer to generate sound. The signal used to produce the sound that comes from a computer speaker is created by the computer's sound card.
III. COMPONENTS INSIDE THE CPU BOX:
1. SMPS:
SMPS stands for Switched-Mode Power Supply. SMPS converts the incoming electricity into proper voltage, and supplies it to other parts inside the CPU box.
2. Motherboard:
Motherboard is the main board that holds together many of the crucial components of a computer, including the central processing unit (CPU), memory and connectors for input and output devices.
3. CPU:
The Central Processing unit is also called as brain or heart of a computer. It is also called as "PROCESSOR". The different component of CPU are-
Arithmetic logical unit:
Here arithmetic logic unit performs all arithmetic operations such as addition, subtraction, multiplication and division. It also uses logic operation for comparison.
Control Unit:
Control unit of a CPU controls the entire operation of the computer. It also controls all devices such as memory, input/output devices connected to the CPU.
4. Disk Drives:
A hard disk is the main storage device found inside a computer. A hard disk consists spindle that holds one or more disks called platters. The platters are coated with a thin layer of magnetic material and data is written on them with the help of read-write head. A hard disk can store several gigabytes (GBs) of data and is used for storing applications and files for a user.
Compact discs are known as optical storage devices. A compact disc can store approximately 700 MB of data. A laser beam is used for storing data on the disc. Compact disc can be of two types-
- CD-R: CD-R is called recordable CD. Data once recorded on CD-R cannot be erased.
- CD-RW: CD-RW is called rewritable CD. Data stored on the CD-RW can be erased and new data can be stored in its place.
5.Ports:
A port is a connector found on the front or back of a computer where you plug in an external device such as a printer, keyboard, scanner, mouse, or modem. This connection allows instructions and data to flow between the computer and the device. These computer ports are also commonly referred to as the Input/output ports (I/O ports).
6. Memory Chips:
Memory chips are one of the important components of computer hardware. Two types of memory chips present on the motherboard are RAM and ROM.
1. Random Access Memory (RAM):
RAM is a read/write memory. Information can be written into and read from RAM. It is a volatile memory. This means that any interruption in power supply results in loss of data in RAM. It retains the stored information as long as the power is switched on. When a computer starts, it loads the operating system into RAM. The amount of RAM installed in a computer decides the number and size of programs that the system can run simultaneously.
2. Read Only Memory (ROM)
This memory uses Metal Oxide Semiconductor Technology. RAM is read-write memory whereas ROM is Read-Only-Memory. This memory is used to store frequently used programs in the system. ROM is a non-volatile memory as it retains the contents even when the power is switched off. In most computers, ROM is used for storing a special piece of software known as BIOS (Basic Input/Output System). It helps in loading the operating system when the computer is switched on.
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