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What is data communications?
Definition
Three Elements• A Sending Unit • A Transmission Channel • A Receiving Unit
Why data communications?
Data Capture at the Information Source
Rapid Dissemination of information
Improved management and centralized control of business data
Data Communications Applications
Remote Job Entry• A batch-processing application (Figure 9-2) • Often employed in computer programming course
Data Communications Applications
On-Line Inquiry• Often used to check the credit-card purchase• Airline Reservations System ─ SABRE http://www.sabre-holdings.com/index.html
Data Communications Applications
Computer-to-Computer Networks• Distributed computers are linked together (Figure
9-4 )
• The precursor of the Internet ─ ARPANET