Saturday 26 November 2011

Explain serial and parallel communication

Explain serial and parallel communication

Serial and Parallel Communication

SERIAL

Serial communication is the method of transferring one bit at a time
through a medium.


Serial transmission is much more common, particularly over longer distances. It is generally much cheaper as only a single channel between sender and receiver is required, eg: The seven bits (plus one parity check bit) making up an American Standard Code for Information Interchange (ASCII) character are transmitted serially in sequence by the sender and are reassembled into the character by the receiver. A common example of a serial interface
standard is Recommended Standard 232 (RS232).


Three things should be considered when discussing serial communications and the equipment to carry this out:

Electrical standards associated with the interface
Mechanical standards associated with the interface
Standards organisations involved

Data transmission may take place in one direction only or it may be bi-directional. There are 3 groups into which the channel can be classified:



asynchronous transmission:
With asynchronous transmission signal timing is not required; signals are sent in an agreed pattern of bits and if both ends are agreed on the pattern then communication can take place.

Bits are grouped together and consist of both data and control bits. If the signal is not synchronised the receiver will not be able to distinguish when the next group of bits will arrive. To overcome this the data is preceded by a start bit, usually binary 0, the byte is then sent and a stop bit or bits are added to the end. Each byte to be sent now incorporates extra control data. In addition to the control data small gaps are inserted between each chunk to distinguish each group.

In asynchronous transmission each bit remains timed in the usual way. Therefore, at bit level the transmission is still synchronous (timed). However, the asynchronous transmission is applied at byte level, once the receiver realises that there is a chunk of incoming data timing (synchronisation) takes place for the chunk of data.

Asynchronous transmission is relatively slow due to the increased number of bits and gaps. It is a cheap and effective form of serial transmission and is particularly suited for low speed connections such as keyboard and mouse.

One example of asynchronous transfer is Asynchronous Transfer Mode (ATM) switching. ATM allows voice, data and video to be transmitted in fixed length cells of 53 bytes.





PARALLEL

Parallel communication is the method of transferring blocks,
eg: BYTEs, of data at the same time.

Parallel transmission requires a separate channel for each bit to be transmitted. Therefore, to transfer a byte, eight channels will be required between the sender and receiver. Added to these eight are additional channels that are needed for control information and if full duplex communication is required then even more channels would be required. Parallel transmission is rare, other than for very short distances, eg: within a computer, eg: data bus, or between a computer and a printer, eg: Centronics printer interface.

1.6 define channel capacity. 
ans:
Transmission Modes
ans:
Simplex

Half Duplex

Full Duplex

Baud and Data Rates

Distinguish between Digital and Analog Transmission

Distinguish between Digital and Analog Transmission

Need of Data communication and Networking?

3. Need of Data communication and Networking?
ans:


  • Signal generation
  • Interfacing
  • Synchronization
  • Exchange Management
  • Transmission System
  • Error Detection and Correction
  • Flow Control
  • Addressing
  • Routing
  • Message formatting
  • Distributed data base
  • Cheap and efficient data transmission over long distances
  • Provides robust communication infrastructure 
  • Enables e-commerce, e-governance, e-services
Signal generation: If you want to send the data to some other location , our device should generate and receive the signal.
Interface: A device must have interface with the transmission system in order to communicate.
Synchronization: whenever two or more devices are sending the data at a time to targeted device, one device should wait, until first divice ends the signal so receiver should know when the transmission of data starts , when it ends.
Exchange Management: for data transmission exchange the resource should be done in efficient manner
Message Formatting: which explains the data can be sent on which format i.e audio or video, text etc
Transmission System Utilisation: it refers to the need to make efficient use of transmission channel, which are generally shared by many communicating devices, various techniques (multi-plexing) are available to allocate the total capacity of a transmission channel among connected devices. Care should be taken to avoid probable
Error Detection and Correction: It is used to correct the data while transmitting from one computer to another computer. It is may not important in case of telephonic conversation.
Flow control: If there is a flow control mechanism is there between the two communication devices, data transmission generates faster than the receiver.
Addressing: when more than two devices share a transmitting facility, source device and destination device should have the identity(or address)
Routing: the routing requires to transmit the data destination
Data communication & networking is needed because it offers cheapest means of data services, allows to share resources and so on.

  • Distributed data base
  • Cheap and efficient data transmission over long distances
  • Provides robust communication infrastructure 
  • Enables e-commerce, e-governance, e-services
Data communication & networking is needed because it offers cheapest means of data services, allows to share  resources and so on.




Thursday 24 November 2011

OCTOBER/NOVEMBER-2011 (C-09)


C-09-CM-403
3453
BOARD DIPLOMA EXAMINATION, (C-09)
OCTOBER/NOVEMBER-2011
DCME VI SEMESTER EXAMINATION
COMPUTER HARDWARE & NETWORKING
Time : 3 Hours]                                                               [Total Marks: 80
PART-A    3*10=30
Instructions: (1) Answer all questions and each question caries three marks. (2) Answers should be brief and straight to t the point and shall not exceed five simple sentences.
1.     List the components inside the computer.
2.     Write the features of chipset
3.     Define form factor of system board
4.     Write short notes on RDRAM
5.     Write short notes on RIMM.
6.     What is a surge protection
7.     List different trouble shooting tools
8.     State the need for networking
9.     Write about coaxial cable.
10. What are the components of IP addressing

PART-B                                              10*5=50
Instructions: (1) Answer any five questions and each question caries ten marks. (2) The Answers should be comprehensive and criteria for valuation is the Content but not the length of the answer.

11. Explain the steps in booting process
12. (a) Explain about ISA. (b) Explain about MCA.
13. (a) Explain about AGP. (b)Explain about CMOS setup.
14. Explain different functional units in CD-ROM drive.
15. Explain the trouble shooting procedure of system board.
16. Explain monitor trouble shooting.
17. Explain the classification of Networks according to their size.
18. Write short notes on: (a) Reapeaters (b) Hubs (c) Switches

signals are continuous in nature.