1st Year Computer Chapter 3 Notes

• What is data communication?
• Write the names of different elements of the data communication system.
• What is a message?  What is the sender?  What is a Receiver?
• What is meant by Communication Medium?
• What is an Encoder?  What is Decoder?
• Define Signals. What are Analog Signals?
• What are digital signals?  What is meant by the encoding of data?
• What is the EBCDIC Code?
• What is ASCII Code? What do you know about Unicode?
• What is the BCD code?   Write any five types of data.
• What are the Modes of Data Communication?
• What is Simplex Mode? What is Half Duplex Mode?
• What is Full Duplex mode? What is Parallel Transmission?
• What is Serial Transmission?  What is Synchronous Transmission?
• What is Asynchronous Transmission?  What is Bandwidth? 
• What is Baseband?   What is Broadband?
• What is communication Media?
• What is Guided Media?  What is Unguided Media?
• What is a Twisted Pair?   What is Coaxial Cable?
• What is Fiber Optic Cable?   What is Microwave transmission?
• What is a Communication Satellite?   What is mobile communication?
• What is a Modem?  What is modulation and demodulation?
• What do you know about Wireless Modem?
• Explain the external modem. Explain the internal modem.
• Define two characteristics of analog signals.
• In this chapter, we will describe how we have arrived at this electronic global village. Computers, telephones, and wireless devices are being linked by network everywhere in the world of connectivity. We are rapidly coming into an era in which we can find almost anything we want online and reach almost anywhere, anytime. When we collaborate, we are sharing information. This sharing can be local or remote. Between individual, local communication usually occurs face to face, while remote communication takes place over distance. Data Communications is the exchange of data between two devices via some form of transmission media such as a wire cable. In other words, we can say that transfer of information or data from one location to another is called Data Communications. The term data communication can generally be defined as the movement of encoded information by means of electrical transmission systems from one computer or device to other computer or device through communication channels (such as cables, wireless media etc).
• Data Encoding : The computer works with binary digits only. Therefore, all data, numeric or nonnumeric, must be converted into binary digits before the computer can understand it. Computers transmit data in the form of binary codes. Both sender and receiver of the data should have same standard rules for both to understand it. Some coding schemes to represent data are :
• BCD Code : (Binary Coded Decimal) is 4 bits code. A few early computers processed BCD numbers but were slower and more complicated than a modern computer, which are able to process alphanumeric (alphabet letters, numbers and other symbols).
• EBCIDIC Code : Extended Binary Coded Decimal Interchange Code is an 8-bit code primarily used by International Business Machine (IBM). This type is intended for efficient transfer between hosts, which use EBCDIC for their internal character representation. For transmission, the data are represented as 8-bit EBCDIC characters. The character code is the only difference between the functional specifications of EBCDIC and ASCII types.