2021 CWSS Computing P1 Solutions

CWSS 2021 PRELIM 4E5N COMP P1 MS Question Answer 1 (a) 11010 = 1 × 26 + 1 × 25 + 1 × 23 + 1 × 22 + 1 × 2 = 11011102 (b) 19C16 = 1 × 162 + 9 × 16 + 12 = 412 2 (a) Control Unit (b) Arithmetic Logic Unit (c) Bus//Data and Address Bus [Don’t Accept] Address Bus 3 (a) • Programs written in programming language are easier for human to understand and also easy to debug. • Machine code is usually in a binary form and it is very lengthy. Not easy to enter the code • Able to use/define functions. (b) Any two: • Program runs at a faster speed as translation are done beforehand. • There is no need for re-compilation to run the program once the translation process is being done. • Syntax errors are detected after the program is run (c) Syntax error // incorrect arrangement in words or symbols used in programming languages OR rules in programming language not being followed. Logic error // error that does not give the output of the intended purpose 4 (a) Any two: • HDD is cheaper for larger amounts of storage space • Expensive to change the technology // HDD are trusted technology • No requirement for the increased speed of SSD (b) Cookies (c) Any three: • Virus // Malware • Unauthorised access // Hacking • Interception of other user’s online transactions (d) Any one: • Check for padlock icon in the internet browser • Use of https:// protocol • Check for the correct website address to prevent phishing • Read privacy policy

2 Question Answer 5 (a) Positive social impact: • Patients at remote places / with limited mobility [1] can get access to healthcare [1] Negative social impact: • Doctors may not have give an accurate diagnosis [1] which patients may not get the right treatment [1] (b) Is it acceptable for robots to replace humans in providing the medical procedures Whose responsibility for failed medical procedures/ misdiagnosis? 6 (a) Any two: • Cost for cables for a short distance is cheaper [1] than the device for wireless transmission [1] • Speed for wired transmission is faster//more reliable //higher bandwidth [1] possible interference that affects the speed for wireless [1] • Higher security for wired transmission [1] as there are possible interception of wireless signals. [1] (b) (i) Network Interface Card (ii) Any three: • 48 bits or 6 bytes • First 24 bits: manufacturer serial number • Next 24 bits: device serial number • Ranges from 00:00:00:00:00:00 to FF:FF:FF:FF:FF:FF (c) (i) Transmits received packets [1] to all connected device [1] (ii) Star Topology

3 Question Answer Deduct 1 mark for any mistake (d) (i) 8-bit binary value Even (Ö) Odd (Ö) 11001011 Ö 10001000 Ö 10010101 Ö (ii) Any one: • Transposition error • When bits still add up to odd/even number • Even number of incorrect bits (iii) Any three: • A value is calculated from the data • The value is calculated using an algorithm • The value is appended to the data to be transmitted • Value is recalculated after transmission • If the values match the data is correct // if the values do not match the data is incorrect 7 (a) Any two: Data Collection Data Processing Data Analysis Data Distribution (b) $A6 Device 1 Device 2 Device 3 Device 4 Device 5 Network Hub

4 Question Answer B$5 $B$2 8 (a) A B C X 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 1 1 1 0 0 1 1 1 0 (b) X = ((NOT A) AND (NOT B) AND C) OR (A AND (NOT B) AND C) 9 (a) Any three: • Retrieval of past records • Input Essential Information • Measurement of data from medical devices • Matching all data with trigger values (b) (i) Boolean String (ii) Line 1, 3, 7 and 10 (5) Line 2, 12 Line 6, 9 (8, 11) (iii) Length Check Format Check 10 • Loop • Input of 20 integers • Selection of even number • Finding Product with selection construct • Output 11 total = 0 INPUT numItems REPEAT subtotal = 0 FOR num = 1 to numItems INPUT qty,price subtotal = subtotal + qty*price NEXT num total = total + subtotal OUTPUT subtotal INPUT numItems UNTIL numItems = "X" OUTPUT total