(Basics of data communication, OSI layers.)
K.K.DHUPAR SDE (NP-II) ALTTC
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Data Communications History
• 1838: Samuel Morse & Alfred Veil Invent Morse Code Telegraph System • 1876: Alexander Graham Bell invented Telephone • 1910:Howard Krum developed Start/Stop Synchronisation
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History of Computing
• 1930: Development of ASCII Transmission Code • 1945: Allied Governments develop the First Large Computer • 1950: IBM releases its first computer IBM 710 • 1960: IBM releases the First Commercial Computer IBM 360
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Main Contributors of Data Comm.
• Transmission Technology • Packet Switching Technology • Internet
– 1967: ARPANET by Advanced Research Project Agency (ARPA) of U.S. – 1975: TCP/IP protocol
• LAN Technology
– DIX-Ethernet & IEEE 802 Networks
• WAN
– 1976: ISO releases HDLC & CCITT releases X.25 (PSPDN)
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Various Networks
• Home Area Network (HAN) • Local Area Network (LAN) • Metropolitan Area Network (MAN) • Wide Area Network (WAN) • Global Area Network (GAN)
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Voice & Data
• In 70’s & 80’s main thrust in Wide Area Networking (WAN) was to put Data on Voice Circuits using Modem & on ISDN lines • In 90’s the trend is reverse. Major Efforts were on putting Voice Over Data using:
– Voice Over Frame Relay – Voice Over Internet – Voice Over ATM etc
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What is Data Communications? •Exchange of digital information between two digital devices is data communication
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Networking
• Networking is the convenient way of making information accessible to anyone, anytime & anywhere. • Evolution of Networking
– Computers handling Large Data were developed
• viz. text, graphics,animation, sound & video
– Improvements in Personal Computers
• Small, powerful & cheap user