This document provides an overview of data communications and its history. It discusses how data communication has evolved from early methods like smoke signals and drum beats to modern digital networks. Key developments mentioned include Morse code, the telegraph, telephone, wireless radio, computers, and the internet. The document also describes basic components of a data communication system including data terminal equipment, data communication equipment, and serial interfaces. It outlines different types of data communication links such as simplex, half duplex, and full duplex.

1. Digital & Data
Communications
Lecture 1

2. What is Data Communications?
• process of
communicating
information in binary
form between two or
more points

3. Data Communications
• Ex. Morse Code
–Combination of DOTS
and DASHES
• 1st Message sent
– “What Hath God Wrought?

4. History of Data Communication
• Smoke or tom-
tom drums
• 26 –wire system

5. History of Data Communication
• 5x5 Matrix
– By 1833, Carl Gauss
– 25 letters(I &J) combined
– 1st deflection-ROW
– 2nd deflection - COLUMN
R1 C1 C2 C3 C4 C5
R2 A B C D E
R3 F G H I & J K
R4 L M N O P
R5 Q R S T U
R6 V W X Y Z

6. History ….
• Telegraph by Morse 1832
• 1844, 1st telegraph line bet.
Baltimore and Washington
D.C.
• 1874, telegraph multiplexer
by Emile Baudot

7. History….
• 1876, 1st telephone system
by Bell
• 1899, Wireless Telegraph
by Marconi
• 1900s, Teletype machines

8. History….
• 1946, ENIAC Mark I & II
• 1950s, Big Blue mainframe
by IBM
• 1951, UNIVAC computers –
1st mass produced

9. History….
• 1968, AT & T systems
interconnection in US
• 1975, Ethernet by Xerox
PARC
• The birth of Internet age..

10. Data Communication Link
DTE DCE DCE DTE
RS -232C RS -232C
Transmission
Medium

11. Data Terminal Equipment (DTE)
• where Info. originates & receives
• Ex.
PC Printers Display
Terminal

12. Data Terminal Equipment (DTE)
PC Printers Display
Terminal
LINE CONTROL UNIT
UART DCE

13. Other DTE Components
• Line Control Unit (LCU) – controls
multiple terminal devices
• UART (Universal Asynchronous
Receiver/Transmitter)
– Parallel-to-serial converter (TX side)
– Serial-to-Parallel converter (RX side)

14. Serial Interfaces
• A connection
between DTE &
DCE units
• RS232C
– Standard interface
rec. by EIA
– Ex. DB-25
DTE DCE

15. Data Communication Equipment
• Signal converter
• Ex.
– MODEM
DTE DCE DCE DTE
Modulator Demodulator

16. Types of Data Communication Link
• Simplex
• Half Duplex
Message
Text
Reply

17. Types of Data Communication Link
• Full Duplex
• Full-Full Duplex
Reply
Reply
Text
Text
Text
Reply

18. Assignment No. 1 (Next meeting)

19. TO Be Continued Next Meeting!