1 hour 30 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use an HB pencil for any diagrams, graphs or rough working. ● Calculators must not be used in this paper. INFORMATION ● The total mark for this paper is 75. ● The number of marks for each question or part question is shown in brackets [ ]. ● No marks will be awarded for using brand names of software packages or hardware. ,



 






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1 (a) The table has six statements about the Von Neumann model for a computer system. Three of the statements are incorrect. Statement number Statement The Program Counter (PC) stores the next instruction to be fetched from memory. The Arithmetic and Logic Unit (ALU) performs mathematical and logical operations.

1 ................................................................................................................................................ ................................................................................................................................................... ...................................................................................................................................................

1 1 0 1 0 1 1 1 1 1 [2] * 0000800000007 * ,



 






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1 ........................................................................................................................................ ...........................................................................................................................................

1 ................................................................................................................................................ ...................................................................................................................................................

1 1 0 0 Write the result after the instruction OR B00001111 is run. [1] (ii) The ACC currently contains the following binary value. 0 1 1 1 Write the result after the instruction XOR #30 is run. [1] * 0000800000016 * ,



 





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2 (a) Convert the denary integer 558 into 12-bit binary and hexadecimal. Binary ....................................................................................................................................... Hexadecimal ............................................................................................................................. [2] (b) (i) Convert the two’s complement binary integer 11100010 into denary. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (ii) Write the smallest and the largest two’s complement binary integers that can be represented in 8 bits. Smallest ............................................................................................................................ Largest .............................................................................................................................. [2] (c) Give one application where Binary Coded Decimal (BCD) is used and justify its use. Application ................................................................................................................................ Justification ............................................................................................................................... ................................................................................................................................................... [2] * 0000800000004 * ,



 






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2 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2] * 0000800000005 * ,



 






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2 ........................................................................................................................................ ........................................................................................................................................... [2] * 0000800000009 * ,



 






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2 ................................................................................................................................................ ................................................................................................................................................... [2] (b) The smartphones use the cell phone network to connect to the WAN. Explain how data is transmitted using the cell phone network. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] (c) Devices that connect to the WAN have an IP address. Complete the following description of IP addresses by writing the missing words. IPv4 is displayed as four groups of 8-bit numbers separated by ........................................ . Each IPv4 address is 32 bits. IPv6 is made of eight groups of 4 ........................................ numbers separated by colons. Multiple consecutive groups of ........................................ can be replaced with a double colon. Each IPv6 address is ........................................ bits. A ........................................ IP address can change each time the computer connects to a network. A ........................................ IP address can only be accessed by other devices in the same LAN and is assigned by the router within the LAN. [6] * 0000800000011 * ,



 





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3 The Control Unit (CU) sends signals to other components on the data bus.

3 9618/12/M/J/25 (b) Registers that are used in the Fetch-Execute (F-E) cycle include the PC, MAR, MDR and the ACC. Identify one other register and describe its role in the Fetch-Execute (F-E) cycle. Register .................................................................................................................................... Role .......................................................................................................................................... ................................................................................................................................................... [2] (c) Explain how an interrupt from an input device will be detected and handled in the F-E cycle. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] * 0000800000003 * ,



 






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3 A computer program uses a digital camera to read the words on an item. The program can read the words that are written on the item, translate the words to a chosen language and then output the words as audio. For example, when used in a supermarket, the program can output the words written on the labels on products. The program uses Artificial Intelligence (AI). (a) Explain how AI is used in the computer program described. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] (b) State two social benefits of the use of AI in the computer program described.

4 The Memory Data Register (MDR) transfers data to the memory address stored in the Memory Address Register (MAR).

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4 (a) Write the logic expressions for the following logic circuit. R S X Y T U X = ............................................................................................................................................ Y = ............................................................................................................................................ [2] * 0000800000006 * ,



 






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5 The MAR stores an address from memory.

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5 An online game has a database that stores data about users and the characters each user creates in the game. Each user can create multiple characters and purchase multiple items for each character. The normalised database has the following design: USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName) (a) Explain the purpose of the table CHARACTER_ITEM in the database. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Underline the attribute, or attributes, that form the primary key in each of the tables. USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName) [2] * 0000800000008 * ,



 






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6 The Accumulator (ACC) stores the result of calculations. Complete the table by writing the three incorrect statement numbers and the corrected statements. Incorrect statement number Corrected statement ............................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ............................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ............................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... [3] * 0000800000002 * ,



 






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6 9618/12/M/J/25 (c) The computer program is released under a commercial software licence. (i) Describe the features of a commercial software licence. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [3] (ii) Explain the reasons why an open source software licence might not be appropriate for the computer program described. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [3]

6 A company has multiple sites in different cities. The company has drivers who deliver products to customers. Each driver can connect to the company’s WAN (Wide Area Network) whilst out of the office using a smartphone. (a) State two ways that a WAN is different to a LAN (Local Area Network).

7 9618/12/M/J/25 (b) Complete the truth table for the logic expression: X = NOT (A AND (B XOR C)) A B C Working space X 0 0 0

7 (a) The following table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction Explanation Opcode Operand LDD <address> Direct addressing. Load the contents of the location at the given address to ACC LDM #n Immediate addressing. Load the number n to ACC STO <address> Store the contents of ACC at the given address ADD #n/Bn/&n Add the number n to the ACC ADD <address> Add the contents of the given address to the ACC INC <register> Add 1 to the contents of the register (ACC) CMP <address> Compare the contents of ACC with the contents of <address> CMP #n Compare the contents of ACC with number n JPE <address> Following a compare instruction, jump to <address> if the compare was True JMP <address> Jump to the given address END Return control to the operating system ACC denotes Accumulator <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A The current contents of memory are: Address Instruction

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9 9618/12/M/J/25 (c) A Database Management System (DBMS) provides data security. (i) Identify two methods the DBMS can use to protect the data in the table USER from unauthorised access. Explain how each method protects the data. Method 1 ........................................................................................................................... Explanation ....................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Method 2 ........................................................................................................................... Explanation ....................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... [4] (ii) The DBMS also supports data integrity. Give two ways that a DBMS can support data integrity.

10 9618/12/M/J/25 (d) (i) Write a Structured Query Language (SQL) script to count the number of items purchased by the user with the username "KAT123". ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [3] (ii) The following changes need to be made to the character with the ID "0002": • level changed to 3 • money changed to 10000.00 Write an SQL script to change the character’s data. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [3] * 0000800000010 * ,



 






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12 9618/12/M/J/25 (d) The main office for the company has four wired computers, one server, two printers, one central switch and a device providing a single point of access for the internet. The network is set up as a star topology. Draw the topology for the main office network. Label all devices. [4] (e) Describe the role of a switch in a network. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [3] * 0000800000012 * ,



 





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13 9618/12/M/J/25 BLANK PAGE * 0000800000013 * ,



 





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15 9618/12/M/J/25 (i) Trace the program currently in memory using the following trace table. Instruction address ACC Memory address

16 9618/12/M/J/25 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. (b) The table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction Explanation Opcode Operand AND #n/Bn/&n Bitwise AND operation of the contents of ACC with the operand AND <address> Bitwise AND operation of the contents of ACC with the contents of <address> XOR #n/Bn/&n Bitwise XOR operation of the contents of ACC with the operand XOR <address> Bitwise XOR operation of the contents of ACC with the contents of <address> OR #n/Bn/&n Bitwise OR operation of the contents of ACC with the operand OR <address> Bitwise OR operation of the contents of ACC with the contents of <address> <address> can be an absolute or symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A (i) The ACC currently contains the following binary value.

22 22 … LDD 10 ADD 12 STO 11 CMP 14 JPE 107 INC ACC JMP 101 STO 10 END * 0000800000014 * ,



 





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22 [3] (ii) State the effect of changing instruction LDD 10 in address 100 to LDM #10 ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (iii) Identify and describe one mode of addressing not given in the table of instructions in part (a). Mode of addressing ........................................................................................................... Description ........................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... [2] * 0000800000015 * ,



 





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