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Different Input and Output Devices

Most of the energy sources involve the conversion of thermal energy to work. 
The device which can convert thermal energy to work is called as heat engine. 
It produces the mechanical work by utilising a part of thermal energy which can be generated by combustion of fuel or in nuclear reactors. 
Some devices can convert the thermal energy to directly an electrical output. 
The thermodynamic laws show the relation between heat and mechanical or electrical or energy. 
No doubt these laws are applicable only for thermal equilibrium not for any rapid changes.

Carnot’s theorem: the most efficient engine possible and is stated in the theorem as well. 
Of all the heat engines working between two given temperatures, none is more efficient than a Carnot engine
We can actually prove Carnot’s theorem on the basis of Clausius statement of the second law of thermodynamics
The first law proves the conservation of energy and can be written as  
Δ Q = Δ U + Δ W
Where Δ Q = Input of heat energy to the system
 Δ U = internal energy change
Δ W = Output in the form of system’s work done

In other words; if an engine produce an output in the form of work by using thermal energy, the net output of work will be equal to net input of thermal energy. Therefore there is no restriction on the amount of thermal energy that can be converted into output like work. 
But according to second law of thermodynamic the amount of work obtained from heat engine which is working between high and low temperature, is limited by the temperature if source (high temperature T1) and sink (low temperature T2).
A reversible theoretical device which is called as Carnot engine, gives the maximum work output for a given thermal input. It operates through cycle of isothermal and adibatic processes. 
Complete engine works in four steps;
•    Imagine the gas and cylinder kept first on the source of heat 
•    Thereafter over a insulator or we can say there is no heat exchanged
•    Within a heat sink or we can say that heat gets removed
•    And at the end we put it back on the insulator

As first law of thermodynamic states that there is no loss or gain of energy, hence the work output of Carnot engine should be equals to the difference between the heat absorbed from the source and passed to the sink. 
The input of heat and output work leads to the definition of efficiency of an ideal Carnot heat engine which is given by;
Efficiency  = Woutput x  100 %

Since, Woutput = Q1 − Q2 and Winput = Q1 
            So   Efficiency= (Q1 − Q2)  / Q1x 100 %

Though the Carnot engine is a imagination only and there is no heat engine which can operate like Carnot cycle as there will be some loss of energy in form of friction, but still it helps to provide idea for increasing the efficiency of practical engines.

The Carnot Cycle: this consist of four operations and that too in succession and they are as follows:
(a)    Isothermal expansion at higher temperature
(b)    Adiabatic expansion between high temperature and low temperature
(c)    Isothermal compression at constant lower temperature
(d)    Adiabatic compression between lower and higher temperatures

When we cross check the efficiency of any engine we find that it depends only on temperatures of source and sink and would be independent of all other factors.
Moreover, all these reversible heat engines which work between same temperatures are actually equally efficient and under no circumstances a heat engine could be more efficient than Carnots.
As we could see on kelvin scale, the temperature could never be negative and when the higher and lower temperatures are found to be finite the efficiency of heat engine is found to be lesser than unity or we could say that the entire heat could never be converted into useful work.
Let us take a summary of the following:
Efficiency of Carnot’s engine is not dependent on the nature of the working substance usually a gas.
Efficiency of Carnot’s engine would depend upon the heat source and sink’s temperature.
Efficiciency of Carnot’s cycle would be 100% if and only if T1 = infinity or T2 = zero K and as these are not possible or could be attained, so the Carnot’s heat engine based on reversible cycle cannot have 100% efficiency.

Instances where the heat sources and sink are at same temperature (T2 = T1) the efficiency of this heat engine would become zero. 
When a refrigerator is working within a closed room with its door closed the refrigerator would reject heat from inside into this room continuously and this will in turn increase the heat of the room slowly and steadily. 
In case the door of the refrigerator is left open the heat rejected by the refrigerator would be more than it takes from the room. 
So in the second instance the temperature of room will indeed increase but in a slower rate than the first instance.
If the heat rejected by the refrigerator could be thrown out directly then the room will cool down gradually and this is the principle of an airconditioner.

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From Wikipedia

Input device

An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system (such as a computer). Input and output devices make up the hardware interface between a computer as a scanner or 6DOF controller.

Many input devices can be classified according to:

  • modality of input (e.g. mechanical motion, audio, visual, etc.)
  • the input is discrete (e.g. keypresses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)
  • the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to:

  • Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the cursor appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.
  • Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

Note that direct input is almost necessarily absolute, but indirect input may be either absolute or relative. For example, digitizing Graphics tablets that do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be setup to simulate a relative input mode where the stylus or puck can be lifted and repositioned.


A 'keyboard' is a human interface device which is represented as a layout of buttons. Each button, or key, can be used to either input a linguistic character to a computer, or to call upon a particular function of the computer. Traditional keyboards use spring-based buttons, though newer variations employ virtual keys, or even projected keyboards.

Examples of types of keyboards include:

Pointing devices

A pointing device is any human interface device that allows a user to input spatial data to a computer. In the case of mice and touch screens, this is usually achieved by detecting movement across a physical surface. Analog devices, such as 3D mice, joysticks, or pointing sticks, function by reporting their angle of deflection. Movements of the pointing device are echoed on the screen by movements of the cursor, creating a simple, intuitive way to navigate a computer's GUI.

High-degree of freedom input devices

Some devices allow many continuous degrees of freedom as input. These can be used as pointing devices, but are generally used in ways that don't involve pointing to a location in space, such as the control of a camera angle while in 3D applications. These kinds of devices are typically used in CAVEs, where input that registers 6DOF is required.

Composite devices

Input devices, such as buttons and joysticks, can be combined on a single physical device that could be thought of as a composite device. Many gaming devices have controllers like this. Technically mice are composite devices, as they both track movement and provide buttons for clicking, but composite devices are generally considered to have more than two different forms of input.

Imaging and Video input devices

Video input devices are used to digitize images or video from the outside world into the computer. The information can be stored in a multitude of formats depending on the user's requirement.

Medical Imaging

Audio input devices

In the fashion of video devices, audio devices are used to either capture or create sound. In some cases, an audio output device can be used as an input device, in order to capture produced sound.


In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world, possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation. I/O devices are used by a person (or other system) to communicate with a computer. For instance, a keyboard or a mouse may be an input device for a computer, while monitors and printers are considered output devices for a computer. Devices for communication between computers, such as modems and network cards, typically serve for both input and output.

Note that the designation of a device as either input or output depends on the perspective. Mouse and keyboards take as input physical movement that the human user outputs and convert it into signals that a computer can understand. The output from these devices is input for the computer. Similarly, printers and monitors take as input signals that a computer outputs. They then convert these signals into representations that human users can see or read. For a human user the process of reading or seeing these representations is receiving input. These interactions between computers and humans is studied in a field called human–computer interaction.

In computer architecture, the combination of the CPU and main memory (i.e. memory that the CPU can read and write to directly, with individual instructions) is considered the brain of a computer, and from that point of view any transfer of information from or to that combination, for example to or from a disk drive, is considered I/O. The CPU and its supporting circuitry provide memory-mapped I/O that is used in low-level computer programming in the implementation of device drivers. An I/O algorithm is one designed to exploit locality and perform efficiently when data reside on secondary storage, such as a disk drive.


I/O Interface is required whenever the I/O device is driven by the processor. The interface must have necessary logic to interpret the device address generated by the processor. Handshaking should be implemented by the interface using appropriate commands like (BUSY,READY,WAIT), and the processor can communicate with I/O device through the interface. If different data formats are being exchanged, the interface must be able to convert serial data to parallel form and vice-versa. There must be provision for generating interrupts and the corresponding type numbers for further processing by the processor if required

A computer that uses memory-mapped I/O accesses hardware by reading and writing to specific memory locations, using the same assembly language instructions that computer would normally use to access memory.

Higher-level implementation

Higher-level operating system and programming facilities employ separate, more abstract I/O concepts and primitives. For example, most operating systems provide application programs with the concept of files. The C and C++ programming languages, and operating systems in the Unix family, traditionally abstract files and devices as streams, which can be read or written, or sometimes both. The C standard library provides functions for manipulating streams for input and output.

In the context of the ALGOL 68 programming language, the input and output facilities are collectively referred to as transput. The ALGOL 68 transput library recognizes the following standard files/devices: stand in, stand out, stand errors and stand back.

An alternative to special primitive functions is the I/O monad, which permits programs to just describe I/O, and the actions are carried out outside the program. This is notable because the I/O functions would introduce side-effects to any programming language, but now purely functional programming is practical.

Addressing mode

There are many ways through which data can be read or stored in the memory. Each method is an addressing mode, and has its own advantages and limitations.

There are many type of addressing modes such as direct addressing, indirect addressing, immediate addressing, index addressing, based addressing, based-index addressing, implied addressing, etc.

Direct address

In this type of address of the data is a part of the instructions itself. When the processor decodes the instruction, it gets the memory address from where it can be read/written the required information. For example:

MOV register, [address] ; to read MOV [address], register ; to write


IN register, [address] ; to read as input OUT [address], register ; to write as output

Here the address operand points to a memory location which holds the data and copies it into/from the specified register. A pair of brackets is a computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.

In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside.

Examples of output devices:

From Yahoo Answers

Question:2.What is the difference between input and output devices? List all input and output devices that can be connected to a computer. Obtain a picture of a computer showing all possible input and output devices. Label it correctly.

Answers:Input devices help in input to a device and output devices handles the output to be fed to another device. For example an input device should have high impedance so that it should not load the output device to which it is connected. Also it should condition the input so that it can be acceptable to the device to which it is fed. Output devices normally help in the device to which they are connected to have low impedance so that they can offer more output and have a smooth functioning. The keyboard is an input device and the monitor, printer etc are output devices. You behave like a teacher in your question like asking others to give a drawing and mention parts. It will take more time and I cannot afford.


Answers:Just quote them their usefulness

Question:I need 20 examples of Input devices, 20 examples of Output devices and 10 examples of storage devices. They can be examples of devices used 30 years ago or today. Any advice on websites, resources, etc.....

Answers:Wikipedia is a good source for lists like this: http://en.wikipedia.org/wiki/Input_device http://en.wikipedia.org/wiki/Output_device http://en.wikipedia.org/wiki/Data_storage_device And these questions have been asked here before: http://tinyurl.com/inputdevice http://tinyurl.com/outputdevice http://tinyurl.com/storagedevice

Question:The name of the device Describe how the device could be used Explain one advantage Explain one disadvantage

Answers:An example of in input device: Microphone - This is an example of an input device because you are putting information into the computer. Other examples include keyboards, computer mice, and cables in which information is sent into the computer. There are really no "advantages" or "disadvantages". An example of an output device: Speakers - This is an example of an output device because the computer is giving out information. Another example is a computer monitor, There are really no "advantages" or "disadvantages". If you want more information, visit this site: http://www.webopedia.com/TERM/I/input_device.html Hope this helps. Neel

From Youtube

Input_Output Devices Part 2 :Computer input and output devices have undergone remarkable development since their existence. This chapter covers the different types of computer input and output devices. The primary function of input devices is 'getting' data and instruction into the computer. Popular input devices are keyboard, mouse, scanner, microphone and webcam. An Output device is any hardware component that can convey information to a user. Common output devices are monitors, printers and sound speakers

Input_Output Devices Part 1 :Computer input and output devices have undergone remarkable development since their existence. This chapter covers the different types of computer input and output devices. The primary function of input devices is 'getting' data and instruction into the computer. Popular input devices are keyboard, mouse, scanner, microphone and webcam. An Output device is any hardware component that can convey information to a user. Common output devices are monitors, printers and sound speakers