1 (a) Describe how packet switching is used to transmit messages across a network [3]

(b) State two benefits and two drawbacks of packet switching as a method of transmitting messages across a network. Benefit 1 Benefit 2 Drawback 1 Drawback 2 [4] , ,

2 (a) Describe serial file organisation as a method of storing data records in a file [2]

(b) State one example of a use for serial file organisation [1]

3 (a) Describe the user‑defined data type record [3]

(b) A programmer defines a record, Order, to store the following data: • account number • order number • order price • order date.

Write pseudocode statements to define this record [4] , ,

4 Numbers are stored in a computer using binary floating‑point representation with: • 12 bits for the mantissa • 4 bits for the exponent • two’s complement form for both the mantissa and the exponent.

(a) Calculate the denary value of the given normalised binary floating‑point number.

Show your working. Mantissa 0 Exponent 1 0 0 0 1 1 1 0 1 1 1 0 1 1 1 Working Answer [2]

(b) Calculate the normalised binary floating‑point representation of – 49.1875 in this system.

Show your working. Mantissa Exponent Working [4] , ,

5 (a) Name and describe two protocols used by the Application Layer of the TCP/IP protocol suite. Protocol 1 Description Protocol 2 Description [4]

(b) Explain the purpose and function of the Application Layer in the TCP/IP protocol suite [3] , ,

6 The truth table for a logic circuit is shown. INPUT OUTPUT A B C D X 0 0 0 0 0 0 0 0 1 1 0 0 1 0 1 0 0 1 1 0 0 1 0 0 0 0 1 0 1 1 0 1 1 0 1 0 1 1 1 0 1 0 0 0 0 1 0 0 1 1 1 0 1 0 1 1 0 1 1 0 1 1 0 0 0 1 1 0 1 1 1 1 1 0 1 1 1 1 1 0

(a) Write the Boolean logic expression that corresponds to the given truth table as the sum‑of‑products. X = [3] , ,

(b) Complete the Karnaugh map (K‑map) for the given truth table. AB CD 00 01 11 10

00 01 11 10

[2]

(c) Draw loop(s) around appropriate group(s) in the K‑map to produce an optimal sum‑of‑products.

[2]

(d) Write the Boolean logic expression from your answer to part (c) as the simplified sum‑of‑products. X = [2] , ,

7 Several syntax diagrams are shown. odd 1 3 5 7 9 even 0 2 4 6 8 symbol % £

@ $ number odd letter A B C D E odd even , ,

(a) State why each number is invalid for the given syntax diagrams.

21 Reason 123 Reason [2]

(b) Complete the Backus‑Naur Form (BNF) for the given syntax diagrams. ::= ::= [2]

(c) A new syntax rule, code, is required. It must begin with a letter, followed by one or two numbers, and end with a symbol.

(i) Draw a syntax diagram for code.

[3]

(ii) Write the BNF for code [2] , ,

8 Complex Instruction Set Computer (CISC) is a type of processor.

Identify four features of a CISC processor. 1 2 3 4 [4] , ,

9 (a) The kernel is the central component of an Operating System (OS).

Outline how the kernel of an OS acts as an interrupt handler [2]

(b) (i) State what is meant by the term multi‑tasking in an Operating System [1]

(ii) Describe how multi‑tasking is implemented in an Operating System [2]

10 Objects and classes form the basic structure of Object‑Oriented Programming (OOP).

(a) Outline the structure of a class [3]

(b) Give three differences between an object and a class. 1 2 3 [3] , ,

11 This binary tree shows an ordered list of integers. 25 4 1 16 9 49 36 64

(a) A linked list of nodes is used to store the data. Each node consists of a left pointer, the data and a right pointer.

−1 is used to represent a null pointer.

Complete this linked list to represent the given binary tree organisation. RootPtr LeftPtr Data RightPtr 25 4 1 –1 –1

[4] , ,

(b) A 2D array is used to store the nodes of the linked list in part (a).

Complete the diagram using your answer for part (a). RootPtr Index LeftPtr Data RightPtr 0 0 25 1 4 2 36 3 1 4 16 5 64 FreePtr 6 9 7 49 8

[4]

(c) The linked list in part (a) is implemented using a 1D array of records. Each record contains a left pointer, data and a right pointer.

The following pseudocode represents a function that searches for an element in the array of records LinkList. It returns the index of the record if the element is found, or it returns a null pointer if the element is not found.

Complete the pseudocode for the function. FUNCTION SearchList(Item : INTEGER) NullPtr −1 RootPtr WHILE NowPtr <> NullPtr IF LinkList[NowPtr].Data < Item THEN NowPtr LinkList[NowPtr].RightPtr ELSE IF THEN NowPtr ELSE RETURN NowPtr ENDIF ENDIF ENDWHILE RETURN NullPtr ENDFUNCTION [4] , ,