2.2. Methods of error detection
A subsection of Computer Science, 2210, through 2. Data transmission
Listing 10 of 27 questions
A file server is used as a central data store for a network of computers. Rory sends data from his computer to a file server that is approximately 100 metres away. It is important that the data is transmitted accurately. Rory needs to be able to read data from and write data to the file server at the same time. Use ticks (3) to identify the most suitable data transmission methods for this application. Method 1 Tick (3) Method 2 Tick (3) Serial Simplex Parallel Half-duplex Duplex Explain why your answer to part is the most suitable data transmission. Identify and describe two methods of error checking that can be used to make sure that the data stored after transmission is accurate. Method 1 Method 2
2210_w17_qp_12
THEORY
2017
Paper 1, Variant 2
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Computers can transmit data using different methods. Describe the three data transmission methods given. Serial data transmission Parallel data transmission Duplex data transmission Data can sometimes be corrupted when it is transmitted from one computer to another, causing errors to be present in the data. Identify and describe three methods of error detection that could be used to see if an error has occurred. Error detection method 1 Description Error detection method 2 Description Error detection method 3 Description
2210_w18_qp_12
THEORY
2018
Paper 1, Variant 2
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Data is valuable to a company. Companies use error detection methods to make sure that data is accurate. One error detection method is the use of a check digit. Explain what is meant by a check digit and how it is used to detect errors. Companies can use a range of security methods to keep their data secure. Identify two security methods that a company can use to keep their data secure and explain how each method can keep the data secure. Security method 1 Security method 2
2210_w19_qp_12
THEORY
2019
Paper 1, Variant 2
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Four 7-bit binary values are transmitted from one computer to another. A parity bit was added to each binary value creating 8-bit binary values. All the binary values have been transmitted correctly. Tick (3) to show whether an Even or an Odd parity check has been used for each binary value. 8-bit binary value Even (3) Odd (3) A parity check may not always detect errors that have occurred in data transmission. State why a parity check may not detect data transmission errors. Give one other error checking method that could be used to check for errors in data transmission.
2210_w20_qp_13
THEORY
2020
Paper 1, Variant 3
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8 bytes of data are transmitted from one computer to another. Each byte of data has a parity bit. The data is also sent with a parity byte. Each bit in the parity byte allows a check to be performed on each column of bits. A parity check is performed on the data and an error is found in one bit. The table shows the data that was received. Parity bit Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Parity byte Identify which bit has an error by giving the Byte number and Bit number. Explain how you found the error. Byte number Bit number Explanation
2210_w22_qp_12
THEORY
2022
Paper 1, Variant 2
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Errors can occur when data is transmitted. Give one reason an error may occur when data is transmitted. Some error detection methods use a calculated value to check for errors. Tick (3) one box to show which error detection method does not use a calculated value to check for errors. A Check digit B Checksum C Echo check D Parity check An automatic repeat request (ARQ) can be used to make sure that data is received free of errors. It can use a positive or negative acknowledgement method to do this. Explain how an ARQ operates using a positive acknowledgement method.
2210_w23_qp_13
THEORY
2023
Paper 1, Variant 3
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A barcode scanning system uses a check digit to check for errors in data on input. Explain how the barcode scanning system operates to check for errors. After a barcode is scanned, data is sent to a stock control system to update the stock value stored for that product. The data is sent to the stock control system using serial simplex data transmission. Explain how the data is sent using serial simplex data transmission. Explain why serial simplex is the most appropriate method of data transmission for this purpose. The data is checked for errors after it has been transmitted to the stock control system. Give two error detection methods that could be used for this purpose.
2210_w24_qp_12
THEORY
2024
Paper 1, Variant 2
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Questions Discovered
27