2 Comunications and the Internet Flashcards
Chapter 2
Cable types
fibre optic cable
twisted pair cable made of copper
coaxial cable with a metal core
Communication types
Simplex
Duplex
Half-Duplex
Data transmission types (from technical point of view)
Electrical pulses
light pulses
Wireless signals
Types of wireless signals
radio signals
micro-wave signals
infrared waves
list data transmission types, which one is the most used.
serial transmission - most used;
parallel
what transmission type is recommended for long distance and what transmission type is recommended for short distance.
long distance - serial transmission
short distance - parallel transmission
Describe serial port pin usages
Two pins are used for data transmission (in/out). The other pins are used just for controlling the port.
Which port type (serial and parallel) is bigger
Parallel port is bigger.
Advantages and disadvantages of parallel data-buses
Advantage: speed
Disadvantage: it takes up place
What is a data bus and where is it used?
A data bus is a cable with a lot of wires and is used inside the computer to connect internal hardware components, for example CPU and RAM.
USB
Universal Serial Bus
Types of peripheral joining
Permanent joining
Plug in cable
Wireless connection
IC
Integrated Circuit
Transcription error
error when copying data, missing or wrong data
Transposition error
Data was copied in the wrong order
ARQ
Automatic Repeat reQeust
The transmitter sends the data packet till it gets a confirmation from the receiver.
Parity check types
even parity and odd parity
With even parity if in a byte there are four 1s what will be the parity bit?
0
What are the limitations of parity check
If there are 2 errors the errors might not be spotted
transposition errrors are not spotted.
Calculate the check digit number with the simple methode for;
4538
4327
What desadvatage has this kind of check?
(4+5+3+8)=20 -> Check Digit X
(4+3+2+7)=16; 16/10=1.6 ->Check sum digit 6
Transposition errors are not identified.
Check dgit calculation with the Luhn methode.
Calucate for 56783
Every second digit is multiplied by 2, and the total must be an exact multiple of 10
Calculate Check digit with the ISBN-10 methode.
Calculate for: 78394
Every digit is multiplied by it,s position in the number and for the check digit is used mod 11.
Calculate the check sum for the number: 566429
32
What do you need to connect to the Internet?
A data transmission connection (wired or wireless)
Internet software
Shared protocols
What does ISP stand for and what does it do?
ISP stands for Internet Service Provider and it provides the following:
To send signals between the Internet and your computer.
It provides email services
Last but not least it can also host web pages
What are protocols?
Protocols are communication standard rules about how data is turned into signals.
What is a web host
A web host stores the information you want to publish on the internet and publishes it for example wix. In wix you make a web site and if you want to publish it wix does it for you.