IGCSE COMPUTER SCIENCE UNIT 2
(DATA AND ENCRYPTION) TEST
QUESTIONS WITH COMPLETE
SOLUTIONS
What are data packets - Answer-Data is split into smaller fragments that makes up the
payload of each packet, which contains:
- Header (Destination and Originating Addresses, Packet number)
- Payload (contents)
- Trailer (indicates the end of the packet, and a checksum for the destination to check if
the transmission was correct)
What does bandwidth mean? - Answer-A measure of how fast data moves.
What is packet switching? - Answer-1. Break down data into packets
2. Send the data through the network
3. Routers control the route taken
4. Destination computer/server reorders the packets into the correct order.
What is serial transmission - Answer-Bits are sent one signal at a time over a single
wire. When one bit is received, the next bit is sent.
What is parallel transmission - Answer-Many bits are sent at the same time over a
number of wires
Advantages of serial - Answer-Before 2000, processors were not fast enough to keep
up with very fast serial transmissions; hence parallel was used to speed up transmission
Now, processors can easily cope with faster serial transmission, which can achieve
faster rates with no crosstalk or skew.
It only requires one wire, meaning cheaper and smaller
Advantages of Parallel - Answer-Data between short distances (within computer or to
nearby devices like printers) can be more quickly transmitted
In a CPU, a full 64 bit binary number can be transmitted in parallel in one clock tick
What is Skew? - Answer-- Each wire will have slightly different properties.
- This will mean that each signal will arrive at their destination at different times.
- Due to this, parallel transmission is best suited for situations where data is to be sent
over a very small distance
- The greater the distance, the greater of an issue that Skew can cause.
(DATA AND ENCRYPTION) TEST
QUESTIONS WITH COMPLETE
SOLUTIONS
What are data packets - Answer-Data is split into smaller fragments that makes up the
payload of each packet, which contains:
- Header (Destination and Originating Addresses, Packet number)
- Payload (contents)
- Trailer (indicates the end of the packet, and a checksum for the destination to check if
the transmission was correct)
What does bandwidth mean? - Answer-A measure of how fast data moves.
What is packet switching? - Answer-1. Break down data into packets
2. Send the data through the network
3. Routers control the route taken
4. Destination computer/server reorders the packets into the correct order.
What is serial transmission - Answer-Bits are sent one signal at a time over a single
wire. When one bit is received, the next bit is sent.
What is parallel transmission - Answer-Many bits are sent at the same time over a
number of wires
Advantages of serial - Answer-Before 2000, processors were not fast enough to keep
up with very fast serial transmissions; hence parallel was used to speed up transmission
Now, processors can easily cope with faster serial transmission, which can achieve
faster rates with no crosstalk or skew.
It only requires one wire, meaning cheaper and smaller
Advantages of Parallel - Answer-Data between short distances (within computer or to
nearby devices like printers) can be more quickly transmitted
In a CPU, a full 64 bit binary number can be transmitted in parallel in one clock tick
What is Skew? - Answer-- Each wire will have slightly different properties.
- This will mean that each signal will arrive at their destination at different times.
- Due to this, parallel transmission is best suited for situations where data is to be sent
over a very small distance
- The greater the distance, the greater of an issue that Skew can cause.
