A-level Computing/AQA/Computer Systems, Programming and Network Concepts/Introduction to Communication and Networking
Definition of this section is available at , page 19.
Communication Methods 
Like a single lane road, all the cars arrive one after another. There is only ever one car going through the check point at any one time.
Define both serial and parallel methods and illustrate where they are appropriate. Consider the effect of distance on the transmission of data.
Baud rate 
The speed at which telecommunicated data is transmitted, measured in bytes-per-second (BPS).
Bit rate 
The rate at which bits are transmitted over a communication path. Normally expressed in bits per second (bps). The bit rate should not be confused with the data signaling rate (baud), which measures the rate of a signal changes being transmitted.
A measure of information or carrying capacity of a signal, expressed as the width of the spectrum of that signal in Hertz. Or the difference between maximum and minimum frequencies in a given spectrum is called the bandwidth of that spectrum.
Asynchronous data transmission 
The ASYNCHRONOUS (ASYNC) format for data transmission is a procedure or protocol in which each information CHARACTER or BYTE is may be transmitted and received at irregular and independent time intervals. The characters or bytes may also be transmitted as a contiguous stream or series of characters.
Start and stop bits 
Describe the purpose of start and stop bits in asynchronous data transmission.
Parity Bits 
Parity is a system in which we use a parity bit to check for errors in a communicating system. Parity bits are generally the most simple way of checking for errors. At the end of a byte sent, an extra bit will be added to the end of the byte. We use two different types of parity bits. These are called even and odd parity bits. If we are using even parity, the bit on the end will ensure that the number of ones sent in the previous data is even. If we are using odd parity, then the bit on the end will ensure that the amount of ones in the sent data is odd.
Handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins. It follows the physical establishment of the channel and precedes normal information transfer.
A protocol is a set of rules which computers use to allow them to communicate. There are many different communications protocols, including WiFi (a low level protocol that stipulates how bits should be converted into radio signals), and IP (a higher level protocol which provides addresses for different locations on a WAN, such as the internet).
A modem is a piece of electronic equipment that takes data from computers and superimposes it onto the carrier signals of public telecommunications systems. This process is called modulation. The equipment also takes previously modulated data from the public telecommunications system and returns them to state that can be read by computers. This process is called demodulation. Modems can be either built-in units or plugged-in units
Local area network (LAN) 
Wide area network (WAN) 
The Internet 
Leased line 
==Dial up== networking Candidates should be familiar with LAN topologies but will not be required to know details of their operation. Candidates should be aware of the advantages and disadvantages of each LAN topology. Candidates should be able to compare local area networking with standalone operation.
Uniform Resource Locator (URL) 
Describe the term URL in the context of Internetworking.
Domain names 
IP addresses 
Explain the term domain name and IP address. Describe how domain names are organised