1.Paige has a computer that has a central processing unit (CPU) based on the Von Neumann model for a computer system. (a) Identify the component within the CPU that controls the flow of data. (b) Identify the component within the CPU where calculations are carried out.

(c) Identify the component within the CPU that stores the address of the next instruction to be processed. (d) Identify the register within the CPU that holds an instruction that has been fetched from memory.

[1] (e) Identify the register within the CPU that holds data that has been fetched from memory.

2. (a) Four denary to 8-bit binary conversions are given. Tick (3) to show if each denary to 8-bit binary conversion is Correct or Incorrect. Denary Binary Conversion Correct (3) Incorrect (3) 145 10010001 179 10110101 11 00010011 100 01100010 [4] (b) Convert the 12-bit binary number into hexadecimal. 1 1 0 0 0 1 0 0 0 0 0 0

Eugene has a web server that stores his online shopping website. Customers access the website using a browser. (a) Describe how the webpages are requested and displayed on the customer's computer.

(b) State three online security threats to Eugene's web server.

3.Arjun uses a scanner to create digital versions of some printed documents. The scanner is attached to his computer using a USB connection. (a) Tick (3) to show if the USB connection uses Parallel or Serial data transmission. Describe your chosen method of data transmission. Parallel Serial Description

(b) Give three benefits of a USB connection.

(c) Arjun uses the Internet to send the digital documents to his friend. He wants to make sure the documents are sent securely. Identify two protocols that can be used to transfer data securely

4.Elsa writes a paragraph in an examination about encryption. There are several terms missing from the paragraph. Complete the paragraph using the list of given terms. Not all terms may need to be used. Some terms may be used more than once. algorithm alphanumeric cookie cypher key padlock plain word processed The data is encrypted using a ....................................................................... . This is an ....................................................................... that is used to scramble the data. The data before encryption is known as ....................................................................... text. When the data has been encrypted it is known as ....................................................................... text. To read the encrypted data it needs to be decrypted using a ....

5.Four 7-bit binary values are transmitted from one computer to another. A parity bit was added to each binary value creating 8-bit binary values. All the binary values have been transmitted correctly. (a) Tick (3) to show whether an Even or an Odd parity check has been used for each binary value. 8-bit binary value Even (3) Odd (3) 10000001 10000010 00101001 00101000 [4] (b) A parity check may not always detect errors that have occurred in data transmission. State why a parity check may not detect data transmission errors.

(c) Give one other error checking method that could be used to check for errors in data transmission.

6.Edith is buying a new computer monitor that displays images using LCD technology. (a) Explain what is meant by LCD technology

(b) State three benefits of LCD technology.

7.Elle uses both CDs and DVDs to store her school projects. (a) Give three similarities between a CD and a DVD.

(b) State one difference between a CD and a DVD

8.A theme park has a game where a player tries to run from the start to the finish without getting wet. The system for the game uses sensors and a microprocessor to spray water at a player as they run past each sensor. Describe how the sensors and the microprocessor are used in this system.

9.Warner says that he has a very good Internet Service Provider (ISP) that provides several services. Five statements about ISPs are given. Tick (3) to show if each statement is True or False. Statement True (3) False (3) Provides access to the Internet for customers Can determine the maximum bandwidth available for customers Monitors the volume of data downloaded by customers Can provide an IP address for the customer Stores the content for all web pages available on the Internet

10.Phishing and pharming are two security issues a user should be aware of when using the Internet. (a) State one similarity between phishing and pharming.p[p'

'(b) Explain two differences between phishing and pharming.

11.A company selling CDs uses a unique 6-digit identification number for each CD title. The rightmost digit (position 1) is a check digit. For example, 6 3 5 0 4 6 3 1 2 4 1 9 check digit digit position identification number The validity of the number and check digit is calculated as follows: multiply each digit by its digit position add up the results of the multiplications divide the answer by 11 if the remainder is 0, the identification number and check digit are valid. (a) Show whether the following identification numbers are valid or not. You must show how you arrived at your answer. Identification number 1: 4 2 1 9 2 3 working:

(b) Find the check digit for this identification number. 5 0 2 4 1 __ working:

(c) Describe, with examples, two different types of data entry errors that a check digit would detect.

12.Kamil is setting up a new computer system to record television programmes. He wants to be able to record, view and then erase programmes that he does not want to keep. He has chosen to use DVD-RAM as an optical storage medium. Explain to Kamil why it is better to use DVD-RAM rather than DVD+RW or DVD-RW.

13.Bytes of data transferred using a serial cable are checked for errors at the receiving end using an even parity check. Can these bytes of data pass the even parity check? (a) 01010101 [1] (b) 11001000 [1] (c) How can any errors be corrected

14.Computer memories are measured in terms of the number of bytes. (a) (i) What is meant by the term byte? [1] (ii) The number of bytes in a Gigabyte can be written as 2x What is the value of x? [1] (b) Flash memories and CD-RWs are used as backing media for computers. Give two differences between these two media.

15.Andrew sends a large document to a printer. (a) State the name for the area of memory used to store temporarily the data being sent to the printer. [1] (b) The printer runs out of paper during the printing job. A signal is sent back to the computer to stop temporarily its current task. Name this type of signal.

16.In a simple symmetric encryption system, each letter of the alphabet is substituted with another. The plain text message: The quick brown fox jumps over the lazy dog. becomes the cypher text message: Zag towvs jumpy dmh coilr mngu zag bfke qmx. (a) (i) Decode this cypher text message. Agbbm Pmubq

[2] (ii) Convert these words to cypher text. Computer Science [2] (b) Both the person who sends the message and the person who receives it need to know what the substitution key is, and they need to keep this secret. A copy of the substitution key has been sent using SSL transmission. (i) What is meant by SSL?

[1] (ii) How does SSL keep the copy of the key secret during transmission?

17.Look at these two pieces of code: A: CLC B: FOR Loop = 1 TO 4 LDX #0 INPUT Number1, Number2 loop: LDA A,X Sum = Number1 + Number2 ADC B,X PRINT Sum STA C,X NEXT INX CPX #16 BNE loop

(a) Which of these pieces of code is written in a high-level language?

[1] (b) Give one benefit of writing code in a high-level language. [1]

(c) Give one benefit of writing code in a low-level language. [1]

(d) High-level languages can be compiled or interpreted. Give two differences between a compiler and an interpreter.

18.When a key is pressed on the keyboard, the computer stores the ASCII representation of the character typed into main memory. The ASCII representation for A is 65 (denary), for B is 66 (denary), etc. There are two letters stored in the following memory locations: Location 1 A Location 2 C (a) (i) Show the contents of Location 1 and Location 2 as binary using 8 bits. Location 1

Location 2 [2] (ii) Show the contents of Location 1 and Location 2 as hexadecimal. Location 1 Location 2 [2] (b) The following machine code instruction is stored in a location of main memory: 1 1 1 1 1 0 1 0 1 0 0 1 0 1 1 1 Convert this binary pattern into hexadecimal. [4] (c) Explain why a programmer would prefer to see the contents of the locations displayed as hexadecimal rather than binary, when debugging his program that reads the key presses.

19.Read this section of program code that inputs twenty (20) numbers and then outputs the largest number input. 1 h = 0 2 c = 0 3 REPEAT 4 READ x 5 IF x > h THEN x = h 6 c = c + 1 7 PRINT h 8 UNTIL c < 20 There are three errors in this code. Locate these errors and suggest a corrected piece of code.