TOPIC 3 : INPUT AND OUTPUT 

3.1
Sometimes the output is an instant reaction to the input. For examples :

(i) 	Zebra-striped bar-codes on supermarket items provide input that permits instant retrieval of outputs - price and item name - right at the checkout counter.

(ii) 	A bank teller queries the computer through the small terminal at the window by giving a customer’s account number as input. The same screen immediately provide the customer’s account balance as output.

(iii) 	A forklift operator speaks directly to a computer through a microphone. Words like left, right and lift are actual input data. The output is the computer’s instant response, which causes the forklift to operate as requested.

(iv) 	A medical student studies the human body on a computer screen inputting changes to the program to show a close-up of a leg and then to remove layers of tissue to reveal the muscles and bone underneath. The screen output the changes, allowing the student to simulate surgery on the computer.

(v) 	A sales representative uses an instrument that looks like a pen to enter an order on a special pad. The handwritten characters are displays as “typed” text and are stored in the pad, which is actually a small computer.

Sometimes input and output may separated by times or distance or both. For examples:

(i) 	Factory workers input data by punching in on a time clock as they go from task to task. The time clock is connected to a computer. The output are their weekly paychecks and report for management that summarize hour per project on a quarterly basis.

(ii) 	A college student writes checks. The data on the check is used as input to the bank computer, and the bank statement that produced once a month as an output.

(iii) 	Charge-card transaction in retail store provide input data that is processed monthly to produce customer bills as the output.

(iv) 	Water-sample data is collected at lake and river sites, keyed in at the environmental agency office, and after a certain periods, reports are produced to show patterns of water quality.

The examples in this section show the diversity of computer applications, but in all cases the process is the same: input - processing-output.

3.2
Input : Getting Data From the User to the Computer

•	Some input can go directly to the computer for processing.
•	Input in this category include bar codes or speech that enters the computer through the microphone.
•	Some input data goes through an intermediate handling. For example, the data is copied from the source document and translate to a medium that a machine can read, such as magnetic disk. 
•	In either case the task is to gather data to be processed by the computer and convert it into some form the computer can understand.

Keyboard

•	is similar to typewriter
•	may be part of a personal  computer or part of a terminal that is connected to a computer somewhere else. 
•	Not all keyboards are the same, for example a keyboard at the McDonald’s computer represent item such as large fries or Big Mac. Figure shows the traditional  keyboard.

Mouse

•	popularized by the Machintosh computer
•	has a ball on its underside, is rolled on a flat surface, usually the desk on which the computer sits.
•	the rolling movement cause a corresponding movement on the screen.
•	moving the mouse allows you to reposition the pointer, or cursor, an indicator on the screen that shows where the next interaction with the computer can take place.
•	The cursor can also be moved by pressing various keyboard keys.
You can communicate commands to the computer by pressing a button on top of the mouse.
•	Some software displays pictorial symbols called icons.
•	A variation on the mouse is the trackball - like an upside-down mouse - you roll the ball directly with your hand.
•	the trackball has two advantages: It does not require a clear surface to roll on, and it can be attached firmly to the keyboard or computer case.

3.3	Source Data Automation 

•	Efficient data input means reducing the number of intermediate steps required between the origination of data and its processing.
•	This is best accomplished by source data automation - using the special equipment to collect data at the source, this activity will generate the data and send it directly to the computer. 

For example : The supermarket bar code, which can be used to send data about the product directly to the computer.

Source data automation eliminates keying, thereby giving two advantages:

(i) 	reducing cost and opportunities for human mistakes.
(ii) 	improve the speed of the input operation.

Magnetic Ink Character Recognition (MICR)

•	machine-reading characters made of magnetized particles.
•	example: the numbers across the bottom of your personal check.
•	Most magnetic-ink characters are preprinted on your check.
•	These characters were added by a person at the bank by using MICR inscriber.

3.4  OPTICAL RECOGNITION

can read numbers, letters, special characters by “looking” at them.
An electronic scanning device converts the data into electrical signals and send the signals to the computer for processing.
Various optical recognition devices can read these types of input:

i)  Optical marks				iv)  Bar codes
ii) Optical characters
iii) Handwritten characters

i) Optical Mark Recognition (OMR)

•	sometimes call  mark sensing
•	a machine can senses marks on a piece of paper
•	example : this technique is used in certain test. The student make a mark using a pencil to a specified answer and the answer sheet is then  graded by a device that uses a light beam to recognize the marks and convert them to computer-recognizable electrical signals.

ii) Optical Character Recognition (OCR)

•	use a light source to read special character
•	convert them into electrical signals to be sent to the CPU.
•	the characters - letters, numbers and special symbols  - can be read by both human and machines. 
•	example: sales tags on the store merchandise.
•	a standard typeface for optical characters , called OCR-A, has been established by the American National Institute.
•	the handheld wand reader is a popular input device for reading OCR-A. In retail stores, the wand reader is connected to a point-of-sale (POS) terminal.
•	This terminal is somewhat like a cash register, but it performs many more functions. When a clerk passes the wand reader over the price tag, the computer uses the input merchandise number to retrieve a description of the item. A small  printer produces a customer receipt that shows the item description and price. The computer calculates the subtotal, the sales tax, and the total. This information is displayed on the screen and printed on the receipt; notice that both screen and printer are output, so the POS terminal is a complex  machine that performs both input and output functions. Finally, some POS terminals include a device that will accept a credit card, inputting account data from the magnetic strip on a customer’s charge card. 

iii) Handwritten characters

•	Machines that can read handwritten characters are yet another mean of reducing the number of intermediate steps between capturing data and processing it. However, not just any kind of handwritten will do; the rules as to the size, completeness, and legibility of the handwriting  are fairly rigid. 

iv) Bar codes

•	Products display at the supermarket have their  own unique numbers, which is part of the Universal Product Code (UPC). This code number is represented on the product label by a pattern of vertical marks, or bars, called bar codes. The zebra stripes can be sensed and read by a bar code reader, a photoelectric device that reads the code by means of reflected light. As with the wand  reader in a retail  store, the bar code reader in a bookstore or grocery store is part of a point-of-sale terminal.The bar code identifies the product to the store’s computer, the code does not contain the price. The price is stored in a file that can be accessed by the computer. The computer automatically tells the point-price on the paper tape for the customer.

Imaging

•	A scanner converts a drawing or document into computer-recognizable form by shining a light on the image and sensing the intensity of the reflection at each point of the image. Scanners come in both handheld and desktop models. If a text image is run through an optical character recognition (OCR) program, then all word and numbers can be manipulated by word processing and other software. Another way to keep photos computer accessible is to have film that was shot with a conventional camera processed onto optical disk instead of prints. 

Data Collection Devices

•	maybe located in a factory.
•	Example: Factory worker use a plastic card to pinch job data directly into a computerized time clock. 
•	Data collection device must be sturdy, trouble-free, and easy to use because that are often located in dusty, humid, hot or cold locations. They are used by people such as warehouse workers, packers, forklift operators, and others whose primary work is not clerical. 
•	Examples of remote data collection devices are machines for taking inventory and reading shipping labels.

Voice input

•	Input your voice in  the computer is known as voice input or speech recognition, is another form of source input.

•	Speech recognition devices accept the spoken word through a microphone and convert it into binary code. 

•	Example: changing radio frequencies in airplane cockpits, reporting analysis of pathology slide viewed under a microscope and allowing physically disabled users to issue commands.

•	Most speech recognition systems are speaker dependent - that is , they must be separately trained for each individual users. The speech recognition system “learns” the voice of the user, who speaks isolated words repeatedly. The voiced words the systems “knows” are then recognizable in the future.

•	Speech recognition systems that re limited to isolated words are called discrete word systems, and users must pause between words.
•	Continuos word system is able to interpret sustained speech , so user can speak normally; so far, such systems are limited by vocabulary to a single subject, such as insurance or the weather.

Touch Screens

One way of getting input directly from the source is to have a human imply point to a selection. The edges of the monitor of a touch screen emit horizontal and vertical beams of light that criss-cross the screen. When a finger touches the screen, the interrupted light beams can pinpoint the location selected on the screen. 

Looking

Delivering input to a computer by simply looking at the computer would seem to be ultimate in capturing data at the source. The principles are reminiscent of making a screen selection by touching the screen with a finger. Electrodes attached to the skin around the eyes respond to  movement of the eye muscles, which produce tiny electric signals when they contract. The signals are read by the computer system, which determines the location on the  screen where the user is looking. 

Resource : Computers & Information Systems, Capron & Perron