Placement — Computer Science paper 2 (theory)

Define the terms hardware and software.

State one reason programmers often use hexadecimal rather than binary.

1. Convert the 8-bit binary number 10110010 to decimal.
2. Convert the decimal number 45 to an 8-bit binary number. You must show your working.

1. Convert the binary number 11001010 to hexadecimal.
2. Convert the hexadecimal number 3F to decimal.

1. State how many bytes there are in 2 kilobytes (kB).
2. Put these units in order from smallest to largest: megabyte, kilobyte, terabyte, gigabyte.

Add the two 8-bit binary numbers below. Give your answer as an 8-bit binary number.

01011011 + 00101110

In the ASCII character set, the letter A has the code 65 and the codes for the capital letters run in alphabetical order.

1. State the ASCII code for the letter D.
2. The lowercase letter a has the code 97. State the character with the code 99.

A bitmap image is 100 pixels wide and 50 pixels high, with a colour depth of 8 bits.

Calculate the file size of the image in bytes. You must show your working.

1. Write the string AAAABBBCC using run length encoding, as a series of frequency/data pairs.
2. State one reason data is compressed.

Two inputs, A and B, take the values 00, 01, 10, 11 in that order.

Write the four outputs, in that order, for each gate.

1. A AND B
2. A OR B
3. A XOR B

State two functions of an operating system.

Explain one difference between a compiler and an interpreter.

Describe the three stages of the fetch–decode–execute cycle.

Explain one difference between RAM and ROM.

State whether each of the following is a PAN, a LAN or a WAN.

1. Wireless headphones connected to a phone by Bluetooth.
2. The computers and printer in one school building.
3. The Internet.

State the purpose of each protocol.

1. HTTPS
2. SMTP

Name the four layers of the TCP/IP model.

Name the social engineering technique described in each case.

1. An email that looks like it is from a bank asks the user to click a link and enter their password.
2. Someone watches over a person's shoulder as they type their PIN at a cash machine.
3. A caller invents a convincing story to persuade an employee to reveal a customer's details.

Describe what is meant by each type of malware.

1. Trojan
2. Spyware

In a relational database, state what is meant by:

1. a primary key
2. a foreign key

A table called Pupils has the fields Name, Form and Score.

Write an SQL query that displays the Name and Score of every pupil with a Score greater than 50, with the highest score first.

A secondary school is considering using facial recognition cameras at its gates so that pupils are registered automatically as they arrive, instead of answering a register in class.

Discuss the ethical and privacy issues the school should consider before introducing the system.

In your answer you should consider the effect on pupils, parents and the school.