Computer hardware notes | Categories of hardware | Examples of hardware | Hardware devices | Computer hardware parts and functions | Computer hardware components | Hardware Notes

Contents :
1. Overview of Hardware.
2. Components of Central Processing Unit (CPU).
3. Types of Input Devices.
4. Types of Output Devices.
5. Computer hardware components

## What is Hardware ?

Hardware of computer are those components that are physical in nature, i.e. they are tangible or can be physically touched. We know that a computer is used for various operations like complex mathematical calculations, storing, merging, retrieving information in a fast way but all these operations cannot be possible without hardware. The hardware can be installed inside and can even be attached to outside of a computer. Hardware components have several hardware devices or physical elements.

The various types of hardware connected to computers are as follows :
1. Central Processing Unit.
2. Memory.
3. Input Devices.
4. Output Devices.
5. Communication or Network Devices.

### Central Processing Unit (CPU) :

The 'brain' of any computer system is the CPU or the processor which has a built-in set of instructions to be implemented. These instructions define the capacity of the computer.
The CPU determines the overall performance of a computer. It calculates and compares as well as activates and controls the operations of all other units of a computer system.

Components of CPU :

1) Arithmetic Logic Unit (ALU) :
The circuitry which carries out all arithmetic and logical calculations are contained in the Arithmetic unit.

i) Arithmetic Unit :
It performs all arithmetic operations like addition, subtraction, multiplication and division and also logical operations such as less than (<), equal to (=) and greater than (>) at very high speed. It is to be noted that arithmetic calculations are limited to additions only like multiplication is repeated addition, e.g, 2 x 3 is 2+2+2, i.e., 6. Similarly, for subtraction, adding the negative of the second number performs subtraction, e.g. x - y is same as x + (-y).
Also, division can be done by multiplying the inverse of a number, e.g., x/y. is same as xx I/y. This is the reason why most processors only have the add function.

ii) Logic Unit :
The Logic Unit helps the CPU in making logical decisions on the basis of instructions received. This is done by the process of logically comparing two data items and taking action accordingly based on the comparison results. In the development of computers, creation of machines that could make decisions was a defining moment, as it transformed the machine from being Just a calculator to one that can perform various tasks.

2) Control Unit (CU) :
The main task of the control unit is to transfer the data and instructions between the different parts of a computer. The control system converts every instruction to a series of control signals which assist in the operation of other parts of the computer.
The control unit is the heart of the CPU which controls the I/O devices and data transfer to and from the primary storage.
The individual instructions of programs stored in the primary storage controls the control unit. The instruction register is used for holding the current instruction and an instruction pointer is used.to hold address of the subsequent instruction. Every instruction is decoded and then implemented correctly which is ensured by the CPU. A parallel can be drawn between the working of the CPU and the traffic police. The control unit decides which action will take place next just like the traffic police which plans according to which road traffic will move or step along with their duration.
The control unit decides what data is required, where it is to be stored, where the results of the operation is to be stored and also send control signals to devices used in the implementation of the instructions. Thus, it monitors the movement of data and instructions in a proper sequence by the use of clock inputs.

3) Registers :
Registers are used to increase the speed of computing process. It is a special type of memory and manages all the processes satisfactory. Registers are the interval memory (inside the microprocessor), which get the information from the Random Access Memory (RAM) and perform the interval calculation and operation for the microprocessor.

4) Buses :
Buses are used to connect more than two devices. So it acts as a pathway and is able to connect the multiple devices. It is a shared transmission medium. For the CPU, bus act as an information highway.

### Input Devices :

Input devices are those devices that are used to feed the data into computer. Currently in market, several types of input devices are present due to the advancement in computer technologies.

## Types of Hardware :

What are the 5 types of hardware ?

Types of Input Devices :

Hardware devices Several types of input devices are as follows :

1) Keyboard :
Keyboards are those input devices that are used to feed the text, commands, etc. into computer. These are the primary input devices used for entering data in computer. It looks like a traditional typewriter but with some additional keys for performing some additional functions. It comes in various sizes and shapes.
A simple layout of a keyboard is shown :

2) Mouse :
It is also a very common input device especially for personal computer. It controls the cursor on the computer screen. It is a palm size box having a spherical ball at its base. When one moves the mouse on a flat surface, the ball senses the movement of the mouse and transfers the corresponding signals to the CPU.
In the classical mouse, there are two buttons (left and right) on the top of the mouse. User has to click these buttons to select or move the items on the screen. A wheel, called scrolling wheel, is housed in between these two buttons.
A typical mouse is illustrated in the figure :

3) Voice Speech Input Devices :
As the name suggests, these devices convert the voice of people into digital form. These devices are used as voice recognition system, if integrated with appropriate software. With the help of these systems, users can operate microcomputers by giving voice commands. Sometimes training is provided to recognition system for a specific voice by vocalizing words to patterns which are already stored in computer.
For example, more than 30,000 words are identified by IBM Voice Type recognise system and are familiarised with individual voices.
As well as some of the systems have the capability to translate one language to another, e.g., from English to Hindi.

4) Digital Camera :
Digital camera is used to feed the images into a computer. There are several imaging tools available that are manipulate the received images with the help of different methods.
Digital camera can only take static pictures. It clicks the pictures, stores them and sends them to computer in the digital format. These pictures are now stored in computer as digital files. These images, stored in the computer, can be printed after manipulation by several graphic programs.
5) Trackball :
Trackball is a special type of mouse. Although the functions of the trackball are same as the traditional mouse, but users do not need to move entire mouse to navigate the cursor on screen.
There is a small, solid ball placed on top of the mouse or positioned left of centre to navigate the cursor. To use this mouse, users need to move the ball only with thumbs in place of moving entire assembly. Hence, user's arm and wrist movements are completely reduced as compared to traditional mouse.

6) Joystick :
Joystick is a cursor control device mainly used for computer gaming and computer aided designing (CAD). The joystick is named so because the pilot uses the control stick to monitor the ailerons and elevators of an airplane. This control stick is a hand-held lever that transmits its pivot coordinates to a computer.
A joystick has one or more than one push buttons that can also be read by computers as desired. One can move the joysticks in all four directions.

7) Touch Screen :
It looks like a monitor or TV screen with the facility of touch sensitivity. Sensitive panel on the screen recognizes the finger touch as an input. Sometimes beams are used by few devices across the touch screen to create a grid. This grid gets interrupted as soon as the finger is brought near to the touch screen.
Touch screen system does not require the mouse and keyboard to feed data into computer. This device is commonly used in public places where only some information is required by the user. The popular example of touch screen is ATM.

8) Touch Pad :
Touch Pad provides a small, touch sensitive area which works as a pointing device in some small computers. The pointer can be moved on screen using movement of finger or a stylus on this pad.

9) Light Pen (Stylus) :
It is like a simple pen mainly used with graphic tablet and touch screen device. With the use of stylus, user can easily write and draw on the device screen, just like writing or drawing on the paper sheet.
A stylus consists of a plastic tip for writing or drawing. It is so small in size that it can be easily fit in the space provided in its a device. The best example of device with that stylus used is Apple iPhone.
10) Scanners :
Scanner is used to scan or read the images. It scans an image and converts it into digital format. Its size ranges from small (hand held) to large (flatbed), depending upon the need. After scanning, software is needed to convert the digital format of image into Viewable format.
Generally, this software is inbuilt with scanner. In present market, several brands of imaging software are available.

### Output Devices :

The result coming out of the computer is known as the output. It can be meaningful or illogical. It can be in several forms like binary format, text format, image form, audio or video format. The physical or tangible device that is used to display the result of computer to the outside world is known as output device.

Types of Output Devices :

Hardware examples In the present day market, several types of output devices are available according to their display Some of the common output devices are illustrated in the following figure.

1) Monitor/Video Display Unit (VDU) :
VDU is an output device that depicts the text, graphics and video in the visual format like a TV. It is basically known as monitor.
The output on the VDU appears in the electrical form for a temporary period of time. This electrical form of output is known as soft copy of output. VDU uses a cathode ray tube for displaying the output or information.
A VDU works same as TV, but it uses the cable through which information is sent directly from the computer.

2) Printers :
Printers are used when one wants an output result on paper. lo present day, there are various types of printers available in the market.
These types of printers arc based upon the techniques they use for printing as well as their print quality and printing speed.
3) Plotters :
Plotter is an output device used to produce the hard copy of output similar to printers except that it is used to print the images in the larger format, e.g, architects draw the map for building construction.
Previously used plotters were very heavy in size. They were mechanical devices with robotic arms for drawing on the paper.
Table plotters were also known as flatbed plotters. They consisted of two robotic arms. A set of colored ink pens, felt pens or pencils were held by these arms for drawing. They positioned at right angles. These arms worked in co-ordination to draw image on the fixed paper. They were very slow as well as complex and huge in size. Plotters took much more time for printing if drawing used to be large and complicated.
The main difference between plotter and printer is that a set of pens is used by plotter to draw images which is not used in printer. For color printing, many plotters use color pens. The output produced by plotters is more accurate, that is why frequently used in CAD (Computer-Aided Design).