1 A hockey club records the number of people that watch each match. An 8-bit binary register is used to store this value. (a) 46 people watch the first match and 171 people watch the second match. Show how the registers would store these denary values as 8-bit binary. Denary value 8-bit binary 46 171 [2] Working space … … … … (b) Give the largest denary value that can be stored in the 8-bit binary register. … [1] (c) The hockey club wants to increase the number of people that can watch each match to 2000. The 8-bit binary register may no longer be able to store the value. Give the smallest number of bits that can be used to store the denary value 2000. … [1] Working space … … … … (d) Electronic data about the final score for the match is transmitted to a central computer 30 kilometres away, using serial transmission. (i) Explain why serial transmission is more appropriate than parallel transmission in this scenario. … … … … … … [3] (ii) The data transmission is also half-duplex. Describe half-duplex data transmission. … … … … [2] (iii) The data transmission uses checksums. Describe how checksums are used to detect errors in data transmission. … … … … … … [3]

1(a) 1 mark each Denary Value 8-bit binary 46 0 0 1 0 1 1 1 0 171 1 0 1 0 1 0 1 1 2 1(b) − 255 1 1(c) − 11 1 1(d)(i) Any three from: − More accurate/reliable/efficient over long distances − Less chance of interference / cross talk − …that will skew / distort the data // less likely to get errors − Data will arrive in order − Serial is cheaper to purchase/install/maintain 3 1(d)(ii) − Transmission in both directions … − …not at the same time // asynchronous 2 1(d)(iii) Any three from: − Calculates a value from the bits/data (to be transferred) // by example/description − Value is appended to the bits/data − Value is transferred with the bits/data − Receiver recalculates the checksum − If both values are different error is detected // if both values are the same the transmission is successful 3 (a) To earn marks, you must correctly convert both denary values (46 and 171) into their 8-bit binary representations. (b) You need to state the largest denary value that can be represented by an 8-bit binary register, which is 255. (c) To score this mark, you must provide the smallest number of bits required to store the denary value 2000, which is 11 bits. (d)(i) You need to provide any three distinct advantages of serial data transmission, such as being more accurate, less prone to interference, or cheaper. (d)(ii) You must explain that half-duplex transmission allows data to be sent in both directions but not simultaneously. (d)(iii) To earn marks, you need to describe the process of checksum error checking, including calculating a value, appending it, transferring it, recalculating at the receiver, and detecting an error if values differ.

2 Julia inputs personal data into her computer. She stores three copies of the data using a hard disk drive (HDD), a solid state drive (SSD) and a USB flash memory drive. (a) Identify three devices Julia can use to input personal data into her computer. Device 1 … Device 2 … Device 3 … [3] (b) Six statements are shown about HDDs, SSDs and USB flash memory drives. Tick (✓) to show which statements apply to each type of storage. Some statements can apply to more than one type of storage. Statement HDD (✓) SSD (✓) USB flash memory drive (✓) it has no moving parts it is non-volatile it can use NAND gates to store data it uses magnetic properties to store data it has the smallest physical size it has the slowest read/write speeds [6] (c) Julia uses a USB connection to transfer data onto her USB flash memory drive. (i) One benefit of using a USB connection is that it is a universal connection. State two other benefits of using a USB connection. Benefit 1 … … Benefit 2 … … [2] (ii) Identify the type of data transmission used in a USB connection. … [1]

2(a) Any three from: − Keyboard − Mouse − Microphone − Keypad − Touchscreen − Touchpad 3 2(b) One mark for each correct row. Statement HDD () SSD () USB flash memory drive () it has no moving parts   it is non-volatile    it can use NAND gates to store data   it uses magnetic properties to store data  it has the smallest physical size  it has the slowest read/write speeds  6 2(c)(i) Any two from: − It cannot be inserted incorrectly − Supports different transmission speeds − High speed transmission − Automatically detected (not connected) // automatically downloads drivers − Powers the device (for data transfer) − Backward compatible 2 2(c)(ii) − Serial 1 For 2(a), you need to identify three distinct input devices that Julia could use to enter personal data. For 2(b), you must correctly tick the appropriate storage types (HDD, SSD, USB flash memory drive) for each of the six given statements. For 2(c)(i), you need to state two benefits of using a USB connection, beyond it being universal, such as its ease of insertion or high transmission speed.

3 A firewall can be used to help keep the data secure that is stored on a computer. (a) The given paragraph describes how the firewall operates to help keep the data secure. Complete the paragraph using the most appropriate terms from the given list. Not all of the terms on the list need to be used. • Accept • Criteria • Hacking • Input • Network • Outgoing • Output • Processor • Reject • Software • Store • Storage A firewall can be … or hardware based. It monitors traffic between the computer and the … The user sets … for the traffic. The firewall will … or … the traffic based on this. It can help prevent … and malicious software that could be a threat to the security of the data. [6] (b) Identify three other methods that could be used to keep the data secure. Method 1 … Method 2 … Method 3 … [3]

3(a) One mark per each correct term in the correct order. − Software − Network − Criteria − Accept // reject − Reject // accept − Hacking 6 3(b) Any three from: − Password − Biometrics (device) − Encryption − Physical methods (e.g. locks) − Two-factor authentication // Two-step verification − Anti-viruses 3 For 3(a), you must correctly fill in all six blanks in the paragraph with the most appropriate terms from the provided list, in the correct order. For 3(b), you need to identify three distinct methods, other than a firewall, that can be used to keep data secure.

3 Five statements are given about the error-checking methods checksum, check digit and parity check. (a) Tick (3) to show whether each statement applies to checksum, check digit or parity check. Some statements may apply to more than one error-checking method. Statement Checksum (3) Check digit (3) Parity check (3) uses an additional bit to create an odd or even number of 1s checks for errors on data entry compares two calculated values to see if an error has occurred will not detect transposition errors sends additional values when data is transmitted from a computer to another [5] (b) Identify one other error-checking method. … [1]

3(a) One mark per each correct row. Statement Checksum () Check digit () Parity check () uses an additional bit to create an odd or even number of 1s  checks for errors on data entry  compares two calculated values to see if an error has occurred   will not detect transposition errors  sends additional values when data is transmitted from one computer to another  () 5 3(b) − ARQ 1

3 (a) Six statements are given about methods of data transmission. Tick (✓) to show if each statement applies to serial simplex, parallel simplex, parallel half-duplex or serial duplex data transmission. Some statements may apply to more than one data transmission method. Statement Serial simplex (✓) Parallel simplex (✓) Parallel half-duplex (✓) Serial duplex (✓) bits are transmitted along a single wire data is transmitted in both directions it is only suitable for distances less than 5 metres bits from the same byte are transmitted one after the other data may not arrive in the correct sequence data is transmitted in both directions, but only one direction at a time [6] (b) A Universal Serial Bus (USB) connection can be used to transmit data from a mobile device to a computer. Give three benefits of using a USB connection for this purpose. Benefit 1 … … Benefit 2 … … Benefit 3 … … [3]

3(a) One mark per each correct row. Statement Serial simplex () Parallel simplex () Parallel half-duplex () Serial duplex () bits are transmitted along a single wire   data is transmitted in both directions   it is only suitable for distances less than 5 metres   Bits from the same byte are transmitted one after the other   data may not arrive in the correct sequence   data is transmitted in both directions, but only one direction at a time  6 3(b) Any three from: − Can charge/power the mobile device (at the same time) − (Uses serial transmission so) data less likely to be skewed / corrupted − Universal / industry standard / connection − Cable can only be plugged in one way // Cannot be inserted incorrectly − Fast transmission speed − Backward compatible − Supports different transmission speeds − Automatically detects device // Automatically downloads drivers 3

Cambridge IGCSE Computer Science · 0478

IGCSE Computer Science (0478) Data transmission past paper questions

Revise IGCSE Computer Science (0478) — Data transmission with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

67 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.