JYSS 2019 P1 Solution

Marking Scheme 1 (a) • 2048/1024 (or 1024 × 2) • 2 GB [2] (b) • Instructions/programs/data • currently in use [2] (c) Any two from: • RAM is volatile, ROM is non-volatile • RAM is temporary, ROM is (semi) permanent • RAM normally has a larger capacity than ROM • RAM can be edited ROM cannot be edited // Data can be read from and written to RAM, ROM can only be read from. [2] 2 Security term Statement Gathers information by monitoring key presses on a user’s keyboard; the information is relayed back to the originator of the software. Cookie Provides a secure connection between web browsers and websites allowing secure transmission of private data. Pharming Uses rules and criteria, set by the user, to help protect a network or system from unauthorised access. Phishing Legitimate-looking email is sent in the hope of gathering personal information; it requires the user to click. Spyware a message given to a web browser by a web server; it is stored in a text file; the message is then sent back to the server each time the browser requests a page from the server Firewall Malicious code installed on the hard drive of a user’s computer; this code will redirect the user to a fake website without the user’s knowledge. [5]

2 3 (a) freeware (b) free and open source software (c) shareware [3] 4 (a) media access control [1] (b) Any two from: – hardware/physical address – unique address/number associated (with network card in) a device/computer – usually 48/64 bits (12/16 hex digits) – first 6/8 digits = manufacturer code/ID of device (NIC) – last 6/8 digits = serial number of device (NIC) [2] 5 (a) [4] (b) 1 1 0 1 0 0 1 0 0 1 1 0 [2] (c) D 2 6 [2] (d) Two from: • It makes the values easier to read/write/understand/debug • Shorter way to represent binary // Uses less screen/display space • Fewer errors made (in data transcription) • Easier to debug (for humans) [2] F A 7 1 1 1 1 1 0 1 0 0 1 1 1 D 3 E 1 1 0 1 0 0 1 1 1 1 1 0

3 6 (a) X = (NOT W AND T) OR (NOT T AND H) [2] (b) [5] (c) Input Working space Output W T H X 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 0 1 1 1 0 [4] 4 marks for 8 correct outputs 3 marks for 6 or 7 correct outputs 2 marks for 4 or 5 correct outputs 1 mark for 2 or 3 correct outputs

4 7 – Line 2: OutRange = 0 – Line 6: should be OutRange = OutRange + 1 – Line 7: NEXT X should be NEXT Count / Line 3: FOR Count = 1 TO 10 should be FOR X = 1 TO 10 [6] 8 (a) • SSD // SD card // Flash memory • Small physical size • Lightweight • Low heat production • Low power consumption • It’s quiet • Fast read/write times (b) • DVD // Blu-ray // USB Flash Drive // SD card • Easy to distribute • Small in size • Cheap to buy • Universal storage therefore compatible with many devices [4] 9 (a) Any one from • To convert it to binary/machine code • The processor can only understand machine code [1] (b) Any two from • Compiler translates all the code in one go… • …whereas an interpreter translates one line at a time • Compiler creates an executable… • …whereas an interpreter does not/ executes one line at a time • Compiler reports all errors at the end… • …whereas an interpreter stops when it finds an error [4]

5 10 (a) [2] (b) Any one from: – an even number of digits are changed – a transposition error(s) has occurred [1] (c) Checksum [1] 11 (a) (4 × 1) + (2 × 2) + (4 × 3) + (1 × 4) + (5 × 5) + (0 × 6) + (8 × 7) = 4 + 4 + 12 + 4 + 25 + 0 + 56 = 105 105/11 = 9 remainder 6 check digit is: 6 [2] (b) 1 mark – No/incorrect check digit 2 marks – Total is 78 – 78/11 … – … gives 7 remainder 1 – check digit should be 1 [3] 12 (a) LEFT (b) MID (c) COUNTIF (d) = $C$2 – E5 [4] Parity Bit 0 1 0 1 0 0 1 1 0 1 0 1 1 1 1 1 1 1 0 1 0 0 0 1

6 13 (a) Any two advantages – no trailing wires (therefore safer, less expensive since no cables) – allows users to work anywhere (portability) – can set up network in places where cable runs are not possible (e.g. outside, historic buildings etc.) [2] Any one disadvantage – limited range – certain items (like filing cabinets) can block the signals – possible to ‘tap’ into WiFi if it isn’t secure – often slower data transfer rate than a wired system – needs additional hardware – number of access points need to match computers [1] (b) Any two advantages • Centralised control of data and resources • Easier to schedule backups of all shared files at regular intervals • Enhances security with the use of built-in security features through the network operating system • Server is accessible remotely and across multiple platforms [2] Any one disadvantage • Higher setup cost due to the need for a higher-performance server. • Administrative costs needed for the maintenance of server and clients [1] 14 Fib Prev2 Prev1 Number OUTPUT 1 0 1 7 1 1 1 6 2 1 2 5 3 2 3 4 5 3 5 3 8 5 8 2 8 [4]

7 15 – correct loop (for, repeat or while loops all work) – correct input – check whether D1 = D4 and D2 = D3 – summation if D1 = D4 and D2 = D3 – calculate percentage and output the value outside the loop [4] sample program T = 0 FOR N = 1 to 50 INPUT D1, D2, D3, D4 IF D1 = D4 and D2 = D3 THEN T = T+1 NEXT N percent = T * 2 OUTPUT percent