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01 - Comp Systems Part 1 (Exam Simulation)

 1. A construction firm, BuildOTech, specialises in designing modern school buildings. The firm uses high end computers with high performance CPUs, GPUs and large amounts of RAM. Give two uses the firm might have for GPUs. (2 marks)

 2. The firm has the need for machines that have large amounts of RAM. Describe what is meant by the term 'RAM'? Note: Define the term RAM, give two explanations for what it does/functionality. (3 marks)

 3. High performance CPUs are also required by the firm, together with the RAM requirement. Describe four characteristics a high performance CPU might have (2 marks)

 4. BuildOTech's computers each have a multi-tasking operating system installed. State the name of and describe two methods that the operating system can use to divide the contents of RAM. (4 marks)

 5. Why do you think it is necessary for BuildOTech to have computers capable of multitasking? Give one example. (2 marks)

 6. The computers in BuildOTech are connected in a LAN and the LAN is connected to the internet. Give one advantage and one disadvantage to the architectural firm of a client-server set up rather than a peer to peer setup. (2 marks)

 7. It is essential that the firm set up a firewall. Listed below are some of the reasons (also important for you to know for your exam) that the firm may use a firewall. Describe the term 'firewall' (1 mark)
Reasons for having a firewall:
==============================
1. Prevent unauthorised access to a network.

2. To restrict applications that are used 
internally that have internet access. 

3. To restrict websites that can be accessed 
from within the company. 

4. To protect the company?s data/intellectual 
property. 

 8. List the data items that will be examined, in the order that they will be visited, when "Lister" is searched for.
alevel_paper1_cert_binarytree_1.png

  John,Rachel, Paul (in this order)

  John,Rachel,Paul(in any order would be acceptable)

  John, Hannah,Bradley

  John, Hannah,Jo

 9. Which of the following options indicates correctly the time complexity of the algorithm used to search for data in a binary search tree?

  O(n2)

  O(log n)

  O(n)

  O(1)

 10. Graph traversal is a more complex problem than tree traversal. State two features that a graph might have, which a tree cannot have, that makes graph traversal more complex. (2 marks)

 11. Data Structures (like binary trees) are categorised on the basis of being static data structures or dynamic data structures. Give three difference between these two types (3 marks)

 12. Explain why the graph in the below figure is not a tree.
alevelcomp_paper1_cert_lionvariety_image1.png

  Because not all nodes have at least two 'child' nodes.

  Because some nodes only have one 'child' node.

  Actually, the graph in the figure could also be a tree. The terms are used as synonyms.

  Because it contains a cycle / cycles.

 13. Fill in the blanks for vertex Forno (4) and Fiver (5).
The graph shown above (for the lions) can
be represented as an adjacency list 
by completing Table 1 below.

Fill in the blanks for Vertex Forno and Fiver

Vertex        Adjacent Vertices
===============================

   1 Onesy               Tupac,Treesy
   2 Tupac               Onesy,Treesy,Forno
   3 Treesy              Onesy,Tupac,Fiver
   4 Forno               ?
   5 Fiver               ?

  4 = Tupac; 5 = Treesy

  4 = Onesy; 5 = Forno

  4 = Tupac; 5 = Onesy

  4 = Tupac; 5 = Forno

 14. Referring to the below adjacency matrix, select the correct statement.
It is also possible to represent the graph
as an adjacency matrix.

For the purposes of this graph assume the
numbers refer to the names of the lions in
the order provided. 

Is the line for Tupac below correct? If not,
what should it be?

Vertex        1   2   3   4   5
===============================

   1 Onesy    0   1   1   0   0        
   2 Tupac    1   0   0   0   0           
   3 Treesy   1   1   0   0   1           
   4 Forno    0   1   0   0   0         
   5 Fiver    0   0   1   0   0 
---------------------------------        

   It is incorrect and should be: 2 Tupac 1 0 1 1 0

  It is incorrect and should be: 2 Tupac 0 0 1 1 1

  It is incorrect and should be: 2 Tupac 1 0 0 0 0

  The line for Tupac is correct: 2 Tupac 1 0 0 0 0

 15. Explain the circumstances in which it is more appropriate to represent a graph using an adjacency list instead of an adjacency matrix. (1 marks)

 16. Read the excerpt below and fill in the blanks for step 1 below.
A computer program stores data input on a stack named dataItems.
The stack has two subprograms to add and remove data items from 
the stack. The stack is implemented as a 1D array, dataArray.

 
 Sub-program Description
--------------------------------
 push()        The parameter is added to the top of the stack
 pop()        The parameter is added to the top of the stack

The main program is shown below (pseudocode):


01 userAnswer = input("Would you like to push or pop an item?")
02 if userAnswer == "push" then
03     push(input("Enter data item"))
04 else
05     print(pop() * 3)
06 endif

Below, shows the decision and steps that need to be made in the "push"
subprogram. Fill in the blanks with the most appropriate statement for
Step 1:

Step 1: _________________________________________________?????
Step 2: If it is not > insert the item
Step 3:  If it is > return/error that the stack is full

  Check if the stack is recursive (so the problem can be called several times until solved)

  Check if the stack is full (pointer = array.length/array.length+1)

  Check if the stack contains at least three elements

  Check if the stack is empty (pointer = array.length - array)

 17. A large social media company stores records about its customers. Read the excerpt below and explain why a hash table is better suited to a linked list to store customer records. (4 marks)
Often an individual customer's record needs
to be accessed. 

This is done by searching using the Customer ID. 

Explain why a hash table is better suited than 
a linked list to store the customer records, 
particularly as the company acquires 
more customers.
 

 18. A charitable organisation is trying to make the works of C.S Lewis available to more people. State an advantage to the website's visitors of the file being compressed. (1 mark)

 19. Lossless takes away some of the information from the original while Lossy preserves all the information from the original. With text the loss of small amounts of information will make it unreadable.
Is the statement above true or false? 

  FALSE

  TRUE

 20. Read the excerpt and context below and complete the boolean expression for Q.
A theatre company offers discounted tickets.
They do, however, have the following conditions.

Let:

A be Customer is under 15
B be Customer has a learner card
C be Customer is over 60
D be Customer has ID to prove age
Q be Discount ticket issued 

(a) Complete the Boolean expression below: 

Q =

  Q = (A OR B) AND (C AND D)

  Q = (A OR B) AND (C OR D)

  Q = (A) OR (C AND D)

  Q = (A AND B) OR (C AND D)

 21. The following expression simplifies to: ~(A * B) * (~A + B) * (~B + B)
Note: ~ = NOT; * = AND; + = OR

  A

  (A+B)

  ~B

  ~A

 22. Explain what the line ten DAT 10 does. (2 marks)
Below is part of a program written using the 
Little Man Computer instruction set. 

This section of code can exit by either 
jumping to the code labelled pass or fail 
depending on what value is in the accumulator
when the code is run. 

Code
=================
 test  SUB   ten   
       BRZ   pass   
       BRP   test
       BRA   fail
 ten   DAT   10

 23. The table below determines whether the program branches to pass or fail given the following values in the Accumulator when it is run. Which row is incorrect, if any?
Starting value in Accumulator      Pass or Fail 
=================================================
        29                         Fail 
        30                         Fail
        31                         Fail

  30 should Pass

  31 should Pass

  29 should Pass

  All the values with the 'Pass or Fail' values are correct in the given table.

 24. The complete program (code) is shown below. What instructions in the program when executed, changes the value in the Accumulator?
alevelcomp_paper1_cert_lmc_fullcode1.png

  Only LDA

  Any from: LDA,SUB,ADD,INP

  The Accumulator value is not changed by instructions. It auto-increments depending on the PC value.

  Only ADD and SUB

 25. Convert the denary number 188 to an unsigned 8-bit binary number.

 26. Convert the denary number 188 to hexadecimal.

 27. Show a representation of denary -119 in 8-bits using sign and magnitude.

 28. Show a representation of denary -119 in 8-bits using twos complement.

  10001001

  11001001

  10101011

  11101000

 29. Using normalised floating point binary representation using 4 bits for the mantissa and 4 for the exponent, represent the denary value 1.75.

  Answer: 0110 1001

  Answer: 0111 0001

  Answer: 0011 1000

  Answer: 1111 0001

 30. Using normalised floating point binary representation using 4 bits for the mantissa and 4 for the exponent, represent the denary value -1.75.
Give your answer in this format: xxxx xxxx (each x represents a 1 or 0)

 31. A bit shift moves each digit in a number's binary representation left or right. Read the excerpt below and select the correct answer.
When shifting left, the most-significant bit is lost, 
and a 00 bit is inserted on the other end.

The left shift operator is usually written as "<<".

0010 << 1  ?  0100
0010 << 2  ?  ______?

  1111

  1010

  1100

  1000

 32. Netflix is a service that allows users to stream movies over the Internet - it has a relational database that stores the films it offers. The database has the field called: Film Title. Why may this be suitable as a secondary key? (2 marks)

 33. Read the excerpt below and identify the law with which the company are complying.
A database stores information about songs on a music 
streaming service.

One of the tables called Song has the fields:

TITLE, GENRE, ARTIST, LENGTH

A band called Nef Beppard removes their permission 
for their songs to be streamed.

The company removes all the songs belonging to Nef 
Beppard from their service.

 34. Write an SQL statement that will remove all songs by Nef Beppard from the table Song.

  None of the listed options are correct

  DELETE ARTIST from FIELDS - WHEN ="Nef Beppard"

  DELETE FROM Song - WHERE Artist="Nef Beppard"

  WHERE Artist="Nef Beppard", DELETE Song

 35. Some games use a 2d game library. Explain why a linker would need to be used after compilation. (2 marks)

 36. What does the following diagram show? Mention the name of the circuit as well as the two gates that are included in the circuit. (3 marks)
Write your answers seperated by commas: x,y,z (use capital letters for the gates)
alevel_paper1_cert_part1_sc_logicgate_1.png

 37. The Boolean expression represented by the Karnaugh map shown below, in its smallest form, is (A AND ¬D) OR (A OR B AND C) OR (B AND¬C OR ¬D)
alevelcomp_paper1_cert_lmc_karnaugh_map.png

  True

  False

 38. A low level instruction is shown below. Is the following statement referring to Immediate,Direct or Relative addressing? >>123 is the address of the data to use
ADD 123

  direct

  mechanical

  immediate

  relative

 39. A large company is building an operating system for a new mobile phone that is soon to be on the market. The code is written using an object-oriented programming (OOP) language. Fill in the blanks for the following advantages of OOP.
Advantages of OOP over Procedural Programming
=============================================
#1. Breaking a problem down into objects naturally
lends itself to teams as different team members
can work on different objects.

#2. Inheritance means that one class can be 
coded and that code used as the base for 
similar objects. This will save the team 
time as they are able to build on work 
already done.

#3. Encapsulation means that objects only 
interact in the way intended and ________
____________________________________ having 
unforeseen consequences. This means there 
are likely to be fewer issues as the team
 combines their code.

  prevents programmers from using the class at all

  prevents unexpected changes to attributes

  prevents access to any object creation methods

  allows easy access and changes to attributes

 40. A fourth advantage has to do with polymorphism. Polymorphism means that code can be written _______________________. This reduces the volume of code the team need to produce.

  that is non-modular in nature

  that has the capability to be set to private, public or static

  that is able to handle different objects in the same way.

  that is able to handle different objects in completely different ways