Papers

Question 2

Calculate the normalised binary floating-point representation of +201.125 in this system Show your working

Answer 2

Mantissa: 0110010010, Exponent: 001000. Also award working marks for converting to binary: 11001001.001; exponent shift: ×2⁸

Question 3

Calculate the denary value of the given normalised binary floating-point number Show your working Mantissa: 1010110011 Exponent: 000101

Answer 3

–20.8125

Question 4

Identify four features of a RISC processor

Answer 4

Low number of instruction formats; Single-clock cycle instructions; Fixed-length instructions; Many general-purpose registers

Question 5

Describe circuit switching as a method of data transmission

Answer 5

A dedicated circuit is required; established before transmission begins; lasts for the whole transmission; data travels the same route continuously; usually bidirectional

Question 6

State one benefit and one drawback of circuit switching

Answer 6

Benefit: No need to reassemble data; arrives in order. Drawback: No other transmission can use the circuit when it’s in use

Question 7

Describe how the layers of the TCP/IP protocol stack interact with each other

Answer 7

Each layer accepts input from the layer above or below; interfaces between layers only interact directly; headers are added as packets move down the layers; operations handled by software; user interacts at the application layer; hardware at the link layer

Question 8

Explain what is meant by a hashing algorithm in the context of file access

Answer 8

A mathematical formula used to calculate an address from a key field

Question 9

Outline two methods of overcoming hash collisions

Answer 9

1. Store record in next free memory space (linear progression); 2. Use an overflow area

Question 10

Describe the user-defined data type set

Answer 10

A composite data type of unordered elements of the same data type; supports set operations like union and intersection

Question 11

Write pseudocode statements to declare the set data type SymbolSet to hold the following set of mathematical operators using the variable Operators

Answer 11

TYPE SymbolSet = SET OF CHAR; DEFINE Operators (‘+’, ‘-‘, ‘*’, ‘/’, ‘^’) : SymbolSet

Question 12

Write the Boolean logic expression that corresponds to the given truth table as the sum-of-products

Answer 12

T = A.B.C.D + A.B.C.D + A.B.C.D + A.B.C.D + A.B.C.D + A.B.C.D

Question 13

Complete the Karnaugh map for the given truth table

Answer 13

See grid in mark scheme – filled correctly with 1s and 0s

Question 14

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

Answer 14

Correct groups drawn around adjacent 1s

Question 15

Write the Boolean logic expression from your answer to part (c) as the simplified sum-of-products

Answer 15

T = A.D + B.D

Question 16

Use Boolean algebra to write your answer to part (d)(i) in its simplest form

Answer 16

T = D.(A + B)

Question 17

Describe the process of segmentation for memory management

Answer 17

Logical address space divided into segments; each has a name and size; during execution segments are mapped to physical memory using a segment map table; segments are indexed with offsets

Question 18

Explain what is meant by disk thrashing

Answer 18

Occurs when excessive paging happens in virtual memory; high disk access rates; more time spent swapping pages than processing

Question 19

State one reason why the attributes would be declared as PRIVATE

Answer 19

To ensure that the attributes are only accessible using the class’s own methods/within the class

Question 20

Complete the class diagram for Pet to include additional attributes and methods

Answer 20

Attributes: PetName : STRING, OwnerName : STRING; Constructor(); SetPetID(APetID : STRING); SetDateRegistered(RegDate : DATE); GetPetName(); GetOwnerTelephone()

Question 21

Complete the BNF for the given syntax diagrams

Answer 21

<operator> ::= + | – | * | /; <label> ::= <letter><digit> | <letter><digit><digit>; <equation> ::= <label> = <label><operator><label>
</label></operator></label></label></equation></digit></digit></letter></digit></letter></label></operator>

Question 22

Draw a syntax diagram for password

Answer 22

Starts with letter or symbol, then digit, then one or two symbols – see diagram

Question 23

Write the BNF for password

Answer 23

<password> ::= <letter><digit><symbol> | <letter><digit><symbol><symbol> | <symbol><digit><symbol> | <symbol><digit><symbol><symbol>
</symbol></symbol></digit></symbol></symbol></digit></symbol></symbol></symbol></digit></letter></symbol></digit></letter></password>

Question 24

Complete the linked list to represent the given binary tree

Answer 24

Add 4 more nodes with correct data and pointers for Orange, Yellow, Indigo, Violet; use -1 for null pointers

Question 25

Complete the diagram to store binary tree in an array of records

Answer 25

Rows with correct pointers: Red(0,1,2), Green(1,3,4), Yellow(2,6,-1), Blue(3,-1,-1), Orange(4,5,-1), Indigo(5,-1,-1), Violet(6,-1,-1)

Question 26

Complete the pseudocode for binary search in a linked list

Answer 26

IF BinTree[NowPtr].Data > Item THEN NowPtr ← BinTree[NowPtr].LeftPtr \n ELSE IF BinTree[NowPtr].Data < Item THEN NowPtr ← BinTree[NowPtr].RightPtr /n ELSE RETURN NowPtr