IGCSE Computer Science Paper 1 Definitions Worksheet: 2.1 Data Transmission Types and Methods and 2.2 Methods of Error Detection (Modules 142–154)
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Key terms
Write what each term means, in your own words.
1
USB drawbacks
2
Evaluate USB
3
error detection
4
interference
5
data loss
6
data gain
7
data change
8
compare sent and received
9
parity bit
Answer Key
IGCSE Computer Science Paper 1 · Modules 142–154 · Student wording will vary for definitions
1USB drawbacks — Limits of USB: short maximum cable length (unreliable over distance), slower speed than some interfaces (old ports slow new devices), and a limited number of ports.
2Evaluate USB — Judge if USB suits a use by weighing benefits (universal, plug and play) against drawbacks (short cable length, limited speed) for the scenario, such as a printer or drive.
3error detection — Checking received data, because it can be damaged in transit and the receiver cannot see the original. Spotting the error is the first step to fixing it.
4interference — Unwanted disturbance to a signal, such as electrical noise or crosstalk, that damages data as it travels and can cause bits to be lost, gained or changed.
5data loss — When some bits or bytes that were sent never arrive, so the message that is received is shorter than the one that was sent.
6data gain — Data gain is when extra bits or bytes that were not sent are added to the data, so the message arrives longer than it was sent. It is a type of transmission error.
7data change — Bits arrive altered, such as a 0 flipping to a 1, so the same amount of data arrives but with wrong values. Comparing sent and received bits shows it.
8compare sent and received — Compare the data sent with the data received. Fewer bits or characters means loss, extra ones means gain, and the same length with different values means change.
9parity bit — One extra bit added to a group of bits (such as 7 data bits) so the total number of 1s follows a rule, even or odd, agreed by sender and receiver. It is used to detect errors.