How user input data to the computer to get processed information

Output in as instant reaction to the input

The central processing unit is the unseen part of a computer system, and user are only dimly aware of it. But user are very much aware of the input and output associated with the computer. They submit input data to the computer to get processed information, the output.

Some time the output in as instant reaction to the input. consider these example ;

• 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 provides the customer's account balance is output.
• Zebra-striped bar codes on supermarket items provide input that permits instant retrieval of outputs-price and item name-right at the chekout counter
• A forklif operator speaks directly to a computer through a microphone. Words like left, righ, and lift are the actual input data. The output is the computer's instan response, which causes the forklift to operate as requested.
• A medical studen studies the human body on a computer screen, inputing changes to the program to show a close-up of the leg and them to remove layers of tissue to reveal the muscles and bone underneath. The screen outputs the changes, allowing the student-without donning a mask, sanitary gloves, or operating gown-to simulate surgery on the computer.
• A sales representative uses an instrument that looks like a pen to enter an order on a special pad. The handwritten characters are displayed as "typed" text and are stored in the pad, which is actually a small computer.

Input and output may sometimes be separated by time or distance or both. 

Here are some examples :

• 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 outputs are their weekly paychecks and reports for management that summarize hours per project on a quarterly basis.
• A college student writes checks. The data on the checks is used as input to the bank computer, which eventually processes the data to prepare a bank statement once a month.
• Charge-card transactions in a retail store provide input data that is processed monthly to produce customer bills.
• Water-sample data is collected at lake and river sites, keyed in at the environmental agency office, and used to produce reports that show patterns of water quality.

The example in this section show the diversity of computer applications, but in all cases the process is the same: input-processing-output. we have already had an introduction to processing. now, in this chapter we will examine input and output methods in detail.

Input: Getting Data from User to the Computer

Some input data can go directly to the computer for processing. Input in this category includes bar codes, speech that enters the computer through a microphone, and data entered by means of a device that converts motions to on-screen action. Some input data, however, goes through a good deal of intermediate handling. such as when it is copied from a source document (jargon for the original written data0 and translated to a medium that a machine can read, such as a magnetic disk. In either case the task is to gather data to be processed by the computer-sometimes called raw data-and convert it into some form the computer can understand.

Keyboard

A keyboard, which usually is similar to a 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 traditional, however. A fast-food franchise like McDonald's, example, uses keyboards whose keys represent items such as large fries or a Big Mac. Even less traditional is the keyboard shown in image below, which is used to enter Chinese characters.

Keyboards

And image below show the complete layout of a traditional keyboard.

Finding your way around a keyboard

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