To interact with a computer we use external devices called input-output or peripheral devices, this is the way a computer has to receive and give information to the user, and without it a computer is practically useless, so the need of input and output devices are the first path to computer organization.
First is the input, input device was there for humans to communicate the data to the computer in various ways and therefor give a task to be processed into output.
After, when the input of data is done the computer need to store it to be able to process it into output, because of the less amount of storage capacity of the CPU (Central Processing Unit), storage devices was there for the purpose of storing a large amount of data so that the CPU can access these data easily and faster.
Output is the final step, the result of input-storage-process-output is given through output devices and before that the computer also need to re-store it in the storage device.
We will see in details, what are the main uses of these devices? And the way it operates with human and computer.
Input Devices:
Definition:
An input device is a peripheral or hardware device, generally external, that is connected or remotely connected to the computer or information appliance.
Input devices are used to provide input which can be understood by the computer such as: raw data, information, command, order, signal… To process input, computer absolutely need an input device, it is the most important part of computers.
Categories:
Input device can be categories into four categories:
Typing devices
Pointing devices
Optical devices
Audio devices
These categories represent the way to communicate with computers and the first path to the input-process-output phase.
Typing Devices:
Typing devices are essentially keyboard, used to insert text or command via button. They are the most effective way to input data to the computer. it use the method of binaries code to input data. Typing devices are very reliable for text and numbers data input.
But they can be ergonomically unsafe if not properly used, inaccurate and difficult for bad typist or paralysis and handicapped users
Basically all computers possess keyboard so it is the primary input of computer system.
Pointing Devices:
Pointing devices are used to input data by movement, here are some example of pointing devices: mouse, joystick, stylus, touch screen.
They are usually used to operate with screen or movement based information, all of them are manually used so easy to manipulate due to simple movement, like the mouse who just consist of pointing and clicking.
One of the main disadvantages is that they are limited in task, mouse and joystick means that you are limited in your work, and touch screen can be less responsive compared to keyboard.
Optical Devices:
Optical devices are mostly used in recognition or video and image capture, in the field of recognition there is the OMR (optical mark recognition) and the OCR (optical character recognition), and many others optical devices like: barcode reader, scanner, handheld scanner, digital camera, webcam…
The OMR reader is used in barcode reader, it scan a mark which indicate the data or information input that is send to the computer to be processed, it is also used in face recognition, finger print scanner, retina scanner and so on. The OCR is for text and character recognition when scanning a text document.
Basically, optical devices are faster than other devices because of a high-speed reading, and are more used by security mean due to their accuracy and reliability.
The disadvantage lies in the raw data, for instance if there is a single change in it, the optical devices may not recognize and therefor give a wrong output to its user
Audio Devices:
Audio devices like his name indicate, is mainly to input an audio data. The devices are: microphone, headset, MIDI keyboard… its process is analogue to digital data convertor.
It allows a user to send audio signals to a computer for processing, recording, or carrying out commands, sometimes the main purpose is to transfer input audio to output audio.
The disadvantage is if the source of audio have a bad signals then all the process are wrong.
Output Devices:
Definition:
Like the input, the output device is also a peripheral and hardware device used to receive the result of the processing date that comes from its input. All computer or information system absolutely need output devices.
Output devices are also known as the way that the computer communicates with human.
Types of Output:
There are three principal types of output devices based on the way they deliver the output data:
Display output
Physical output
Audio output
Display Output:
They are commonly monitors, screen or light based devices called Visual Display Unit (VDU). It is the primary output devices and it can also be used as a input device, the computer will display the contents of the information on the screen to permit the users read or see what are the processes done to the input data, that is called soft copy which mean temporary data copy.
Display output devices is also the wall between computer-language and human-language, without it human can’t understand what the computer try to communicate.
Usually, display outputs are called video displays or 2 dimensional displays, like:
Television sets
Computer monitors
Head mounted display
But there are also called segments displays, composed of several segments that switch on and off to give appearance of desired output, they are display that can only show numeric numbers or alphanumeric character, like calculators or digital watch and so on.
The advantages of display device is that you can see the output of a computer program and also use your computer easily by giving it commands from a Command Line Interface or use your Pointing device such as Mouse to point and click to do a task from a Graphical User Interface (GUI). It is fast to acquire, more economical and easily transmittable.
In another hand, disadvantages are that the output is temporary because of the need of power supply and can cause visual problem for users.
Physical Output:
Physical output or hard copy is the permanent output; the most common way to get it is the printer.
There are two type of printer:
Impact printer: use the typewriter approach, impact of between the ink ribbon and the paper. E.g. dot-matrix printers.
Non-impact printers: use electro-static chemicals and ink-jet technologies, can produce colour printing. E.g. laser printer, ink-jet printer
So, printer is the principal output devices in terms of physical output; it can produce high-quality printing, can produce a large amount in short time.
The disadvantages are the cost; printing is expensive due to its hard copies compared to soft copies that just need to be displayed.
Audio Output:
Audio output devices refer to any devices that are attaches to a computer for the purpose of playing sound, such as speech or music. It can also refer to the sound of a computer sound card.
Here are some examples of audio output devices with their uses:
Speakers: it is the most common type of audio output device; they can be attached to a computer using variety of audio plugs. It requires a separate energy supply to be operational.
Headphones: they are another type of audio output device. Variations on the headphone concept include ear buds, which fit inside the ear, and headsets, which include both headphones and a microphone. It doesn’t requires a separate power supply.
Sound card: it is a computer component that converts information from digital audio files into electronic sound signals. These signals are then passed on to an audio output device, such as speakers or headphones. Although sound cards do not themselves play sound, they do output audio signals. For this reason, they can be considered audio output devices.
Without an audio output device, you will miss audio cues from the computer such as error beeps and other important system messages alerting you to system problems. This keeps you in sync with your computer, allowing you to more effectively recognize and identify issues.
There are no real disadvantages for audio output devices, just it need some additional hardware such as sound card and additional power supply, and the possibility of making noise.
Storage Devices:
There are primarily three types of storage a computer possess, first the primary storage, which is more popularly called simply memory; the secondary storage, which is more popularly referred to as simply storage, and finally the offline storage referred as movable storage.
Primary Storage:
Primary storage is where a computer stores data on a temporary basis so it can process the data. Think of primary storage as “short term memory”. Primary storage is a type of memory that is directly accessible to a computer processor and it is volatile because it is temporary in nature and is erased when the power is turned off.
The main primary storages are:
RAM (Random Access Memory)
ROM (Read Only Memory)
Data the computer is currently processing or data which the computer knows it is about to need for processing is stored in primary storage. Memory in primary storage can be accessed quickly by the CPU. Its storage capacity, however, is much smaller than what can be stored in secondary or tertiary storage. Computers need just enough primary storage to function and temporarily hold anticipated amounts of data for processing.
Secondary Storage:
Secondary storage is where a computer stores data it is not currently processing but which it may need at some later time. Secondary storage can be thought of as “long term memory”, or storage, and it is non-volatile in nature because data remains intact even when power to a computer is turned off. Operating systems, documents, music files and so on are typically stored in a secondary storage device. They can also be external for movement and transport.
The main device for secondary storage is the hard disk drive (HDD). The computer’s largest secondary storage location is its hard disk drive, or just hard drive. Hard drives are platters like dishes which are stacked top, middle, and bottom to make one unit. Hard drives are mechanical devices which store data magnetically. They are considered permanent storage.
Among the advantages of a hard disk drive is its storage capability, from Megabyte to Terabyte. Hard disk drives are durable, with metal casings built around their inner components. Hard disk drives are read/write. They can be read over and over and they can be modified, or written to, over and over.
Offline storage:
Offline storage is storage media which can be inserted into the computer and used but which can then be removed from the computer and stored elsewhere. It can also be external sources which are connected to the computer and then disconnected, like floppy drives, CD drives, DVD drives, USB flash drive, and Blu-ray drives.
Floppy drive is an old form of storage, its capacity is very few up to 1 or 2 Megabytes so it isn’t used nowadays, but it is categorised as offline storage because they are non-volatile and be able to read or written to over and over again.
CD drive (Compact Disk) and DVD drive (Digital Video Disc) store data on shiny discs, the capacity of CD drive is up to 700 Megabytes and the DVD drive is 4.7 Gigabytes and 8.5 Gigabytes on a double layer DVD, they are very compact and portable storage with a good amount of storage, so it is the primary commercial storage device, used for video, audio, software, games and so on. But the disadvantages are that it can be infected by virus if used with bad intention, also if the layer of the disk gets damaged like scratch the computer will not be able to read anymore so a loss of data.
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USB flash drive, which is the most portable storage device with a great amount of storage, they can support 128 Megabytes to 256 Gigabytes, and it is the easiest way to carry data from place to place due to its connectivity via USB port. Unfortunately, USB flash drive is very fragile, easily breakable, and can be easily get corrupted or infected by viruses, so basically used for a short amount of time before it is useless.
Conclusion:
After describing and explaining input, output, and storage devices, we can see that the utilisation of computer in operations, functions, and processes are based within these devices, without just one of them work can’t be done.
These are all interaction between computers and humans that are necessary to achieve the perfect use of computer, it is studied in a field called human-computer interaction.
Nowadays these interactions are appearing more and more frequent in daily life, with better speed and accuracy due to the evolution of technologies, and human are becoming more reliable in computers than before.
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