Learn Extracted exam questions A-Level Computer Science 9618 Computer Science November 2024 Question paper 13
9618 Computer Science November 2024 Question paper 13
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1 (a) Describe the operation of a 2-input XOR gate [1]
(b) Write the logic expression for the following logic circuit. C X B A X = [2]
(c) Draw the logic circuit for the logic expression: X = ((NOT A AND (B AND C)) OR (B NAND C)) AND NOT A X C B A
[2] , ,
2 A memory buffer uses Dynamic RAM (DRAM).
(a) Identify two differences between DRAM and Static RAM (SRAM). Difference 1 Difference 2 [2]
(b) Explain how a memory buffer is used when a computer is transferring data to its magnetic hard disk drive [4] , ,
3 A car has an automatic braking system.
A sensor is used to measure the distance to objects that are in front of the car.
The car automatically brakes if an object is too close to the front of the car or the distance between the car and the object is decreasing too quickly. The closer the object is to the front of the car, the harder the car brakes so that the car slows down more quickly.
Explain the reasons why the automatic braking system of the car is a control system [3] , ,
4 A company makes ice cream and sells it to shops.
The ice cream is made in batches: a large quantity of one type and flavour of ice cream that is then split into smaller quantities for sale.
The company’s owner has designed a relational database, ICECREAM, to store data about their ice cream and customers.
Some of the tables in the database are given. The database is not normalised.
BATCH(BatchID, Type, Flavour, Size, SellingPrice, EndDate)
CUSTOMER(CustomerID, CompanyName, EmailAddress, TelephoneNumber)
SALE(SaleID, BatchID, CustomerID, Quantity, Date)
(a) Identify two foreign keys in the table SALE and the table that each foreign key references. Foreign key 1 Table name 1 Foreign key 2 Table name 2 [2]
(b) Write an SQL script to return the total quantity of ice cream sold to the customer with the ID of 0034E in the year 2023 [3] , ,
(c) The table definition for BATCH is repeated here:
BATCH(BatchID, Type, Flavour, Size, SellingPrice, EndDate)
Sample data for the table BATCH is given: BatchID Type Flavour Size SellingPrice EndDate KlV12 Plain Vanilla 1 2.20 12/12/2024 RlC14 Plain Chocolate 0.5 1.80 12/12/2024 TYL1 Non-dairy Lemon 0.5 2.10 01/02/2025 FYV2 Non-dairy Vanilla 0.25 1.50 02/02/2025 BIV13 Plain Vanilla 1 2.20 02/02/2024
(i) Write an SQL script to define the table BATCH.
Include constraints (restrictions) on the data that can be entered into each field where appropriate [5] , ,
(ii) The table BATCH is not normalised.
Normalise the database table BATCH.
Write the table definitions for your new tables.
Identify any primary and foreign keys in your tables.
Do not change or include the tables CUSTOMER and SALE [4]
(d) Complete the following table by defining each database term. Database term Definition Entity Attribute [2] , ,
(e) A Database Management System (DBMS) supports data integrity.
Explain how a DBMS supports data integrity [3] , ,
5 A computer programmer writes programs that are distributed with a software licence.
(a) Complete the table by writing the type of software licence each statement describes. Statement Software licence A fee is charged for the software. The source code cannot be accessed. Users do not get a free trial Users can try the software before buying it. Users may not be able to access all features during the trial Software is usually free of charge. Users can access the source code and alter the program to their needs [3]
(b) Explain the reasons why it is important for the computer programmer to join a professional ethical body [3] , ,
6 A computer system stores text, images and sound.
(a) A character set is used to represent characters in a computer.
Identify and describe one character set. Character set Description [2]
(b) The colour of each pixel in a bitmapped image is represented by 8 bits.
(i) State the largest number of different colours that can be represented by 8 bits [1]
(ii) State one drawback of increasing the number of bits that represents each pixel in the bitmap image [1]
(iii) A bitmap image can be compressed using lossy compression.
Explain the reasons why lossy compression is often suitable for a bitmap image [2] , ,
(c) (i) Explain how an analogue sound wave is converted into digital data [2]
(ii) Describe one method of compressing a sound file using lossy compression [2] , ,
7 The following table shows part of the instruction set for a processor. The processor has two registers, the Accumulator (ACC) and the Index Register (IX). Instruction Explanation Opcode Operand LDM #n Immediate addressing. Load the number n to ACC LDD
Direct addressing. Load the contents of the location at the given address to ACC LDI Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC LDX Indexed addressing. Form the address from + the contents of the index register. Copy the contents of this calculated address to ACC LDR #n Immediate addressing. Load the number n to IX ADD #n/Bn/&n Add the number n to the ACC ADD Add the contents of the given address to the ACC SUB #n/Bn/&n Subtract the number n from the ACC SUB Subtract the contents of the given address from the ACC INC(a) The current contents of memory are shown: Address Data 50 54 51 55 52 50 53 52 54 100 55 25 56 50
The current contents of the ACC and IX are shown: ACC 50 IX 45
Complete the table by writing the content of the ACC after each program has run. Instructions ACC content 1 LDD 50 ADD #4 ADD 54 2 LDI 53 DEC ACC ADD 56 3 LDM #55 SUB #5
[3] , ,
(b) The instruction set also includes these bit manipulation instructions: Instruction Explanation Opcode Operand AND #n/Bn/&n Bitwise AND operation of the contents of ACC with the operand AND
Bitwise AND operation of the contents of ACC with the contents of XOR #n/Bn/&n Bitwise XOR operation of the contents of ACC with the operand XOR Bitwise XOR operation of the contents of ACC with the contents of OR #n/Bn/&n Bitwise OR operation of the contents of ACC with the operand OR Bitwise OR operation of the contents of ACC with the contents of 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. &4AExplain how bit manipulation can be used to clear the data in an 8-bit register.
Write the bit manipulation instruction that will be used. Explanation Instruction [3] , ,
8 (a) Convert the hexadecimal number 1FAB into denary. Working Denary value [1]
(b) Explain how to convert the two’s complement integer 10011111 into denary. Give the denary value after conversion. Explanation Denary value [3]
(c) Describe the difference between a right logical binary shift and a right arithmetic binary shift [2] , ,
9 A computer is connected to a Local Area Network (LAN) that connects to a Wide Area Network (WAN).
(a) Describe the characteristics of a WAN [2]
(b) Copper cable can be used to transmit data in a network.
Complete the table by identifying and describing two other transmission media that can be used to transfer data in the WAN. Transmission medium Description [4] , ,
(c) The computer on the LAN is used for real-time video conferences, where people connected to the internet communicate in real-time using video and audio.
Explain how bit streaming is used in a real-time video conference [4]
(d) The LAN has a router. The router has a public IP address and a private IP address.
(i) State the purpose of a public IP address and a private IP address. Public IP address Private IP address [2]
(ii) The LAN uses subnetting.
Describe the purpose of subnetting in a network [2] , ,