9608_w21_qp_13
A paper of Computer Science, 9608
Questions:
9
Year:
2021
Paper:
1
Variant:
3
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1
Convert the following two’s complement binary integer into denary. Show your working. Working Answer Convert the following unsigned binary integer into hexadecimal. Convert the following denary integer to Binary Coded Decimal (BCD). Give two examples of practical applications of BCD. An encryption routine replaces each character in a short message with a different character. For example, the following table shows how the routine encrypts the word ‘HELLO’ by adding 3 to the ASCII denary value of each character. Original character H E L L O ASCII denary value ASCII denary value + 3 Encrypted character K H O O R The ASCII value of the character A is 65. Complete the table to show how the routine will encrypt the word ‘WANDS’. Original character W A N D S ASCII denary value ASCII denary value + 3 Encrypted character
1. Theory Fundamentals  →  1.1. Information representation
2. Fundamental Problem-solving and Programming Skills  →  2.2. Data representation
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2
Daniel is creating a sound file for a school project. Daniel records the sound using a sampling rate of 44.1 kHz and a sampling resolution of 16 bits. State what is meant by a sampling rate of 44.1 kHz. State what is meant by a sampling resolution of 16 bits. Daniel needs to write a report about the sound he is using for his project. He will use a keyboard to write this report. Describe the basic internal operation of a keyboard.
1. Theory Fundamentals  →  1.1. Information representation
Open
3
Describe what is meant by a Public IP address and a Private IP address. Public IP address Private IP address Complete the following paragraph that describes the sequence of events when a user requests a page from a website. The user enters the Uniform Resource Locator (URL) into the address bar of the . The domain name is taken from the URL and sent to a Domain Name Service (DNS). This stores of domain names and their matching IP addresses. If it finds the domain name, it sends the IP address to the . If it does not find the domain name, it sends the request to .
1. Theory Fundamentals  →  1.2. Communication and Internet technologies
Open
5
Describe how the following registers are used in the fetch-execute (F-E) cycle: • Current Instruction Register (CIR) • Program Counter (PC) • Memory Data Register (MDR) • Memory Address Register (MAR). Describe the roles carried out by the Arithmetic and Logic Unit (ALU) and the system clock. ALU System clock The following table shows part of the instruction set for a processor. The processor has one general purpose register, the Accumulator (ACC), and an Index Register (. Instruction Explanation Op code Operand LDM #n Immediate addressing. Load the number n to ACC CMP Compare the contents of ACC with the contents of ADD Add the contents of the given address to the ACC INC Add 1 to the contents of the register (ACC or JPE Following a compare instruction, jump to if the compare was True STO Store the contents of ACC at the given address END Return control to the operating system The instructions in the processor’s instruction set can be grouped according to their function. Identify one instruction group for each instruction in the following table. Instruction Instruction group LDM #12 ADD 21 STO 21 CMP 21 JPE 01 Some assemblers scan the assembly language program twice; these are referred to as two-pass assemblers. Complete these two sentences by writing the missing terms. In the first pass the table is generated. In the second pass the program is converted into code.
1. Theory Fundamentals  →  1.4. Processor fundamentals
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7
Tick (3) one box in each row to identify whether each measure is an example of data verification or data validation. Measure Data verification Data validation Parity check Double entry Format check Identify one measure of data verification not given in part . Identify one measure of data validation not given in part .
1. Theory Fundamentals  →  1.6. Security, privacy and data integrity
1. Theory Fundamentals  →  1.8. Database and data modelling
2. Fundamental Problem-solving and Programming Skills  →  2.1. Algorithm design and problem-solving
Open
9
A company uses a relational database. The company stores data about its customers and their bank details. Explain the ways in which the database can be set up to only allow certain people to see the bank details. The database contains the following tables that store data about suppliers and stock. SUPPLIER(SupId, SupName, SupAddress, SupPhone, SupContactName) STOCK(StockId, SupId, StockName, StockImage, NumberInStock) Write Data Manipulation Language (DML) statements to return the supplier name, phone number and contact name, and the number of items in stock for the item with the stock ID of D930. The stock price needs to be included in the stock table. $10.55 and $299.99 are two examples of stock prices. Write Data Definition Language (DDL) statements to insert the attribute StockPrice into the table STOCK. Three examples of items stored in the data dictionary of a relational database are: Item Purpose Field name to store the names of fields so they cannot be repeated in a table Primary key to uniquely identify each record in a table Validation rule to ensure that data entered is sensible Identify three other examples of items stored in a data dictionary and give the purpose of each. Item 1 Purpose Item 2 Purpose Item 3 Purpose Draw one line from each database term to its matching description. Database term Description An attribute that could be a primary key but is not selected to be a primary key Logical schema An attribute in one table that is a primary key in another table Referential integrity The overview of a database structure Query processor An attribute or set of attributes that uniquely identifies each tuple Primary key Data between linked tables is consistent Secondary key Changing data to see what would happen in different scenarios The part of the DBMS that allows a user to search for data
1. Theory Fundamentals  →  1.8. Database and data modelling
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