Section 6 - Communication Methods Flashcards
What does data communication involve?
Sending and receiving data from one device to another
Where does data communication occur?
Within the CPU and between the CPU and it’s peripheral devices
What are the 2 methods of data communication?
- Serial
- Parallel
How does serial data transmission work?
Bits are sent via an interface one bit at a time over a single wire from the source to the destination
How does parallel data transmission work?
Several bits are sent simultaneously over a number of parallel wires
Where is parallel data transmission used in?
- Integrated circuits
- RAM
What is skew?
An issue that occurs due to each individual wire in parallel data transmission having slightly different properties, meaning bits may travel at slightly different speeds
What are the advantages of serial transmission?
- Connectors are much smaller and simpler, reducing the associated costs
- “Crosstalk” can create interference between parallel lines, resulting in corrupted data that must be retransmitted
- Serial links are more reliable over long distances
- Because of the lack of interference, serial transmission can operate at a much higher frequency and therefore result in a higher net data transfer
What is bit rate?
The speed at which data is transmitted serially
What is bit rate measured in?
Bits per second
What is baud rate?
The rate at which the signal changes
What is the bit rate of channel?
baud rate * number of bits per signal
What is baseband mode?
Only 2 voltage levels are used, representing 0 and 1. In this case the baud and bit rate are the same
What is bandwidth?
The range of frequencies that a transmission medium can carry. The large the range, the greater the amount of data that can be transmitted in a fixed amount of time
What is bandwidth expressed in?
Bits per second
What is latency?
The time delay between the moment that the first byte or packet is transmitted, and when it is received at its destination
What is parity?
What is a protocol?
A set of rules relating to communication between 2 devices
What is a symbol?
A particular pattern of bits that is represented by a signal
What is synchronous transmission?
Where a clock is used to time when signals are sent. It is used within the busses of a computer’s processor in the fetch-execute cycle
How can synchronous transmission be used?
For transmitting information in real-time systems
What is asynchronous transmission?
Where one byte at a time is sent, with each character being preceded by a start bit and followed by a stop bit. The start bit alerts the receiving device and synchronises the clock inside the receiver ready to receive the character
