task 1 – getting it! - arkacton.org · web viewhomework 12: logic gates 1hr. bbc bitesize,...

OCR Computer Science: Year 11 Homework pack Spring 1Name: ……………………….Our spring 1 Homework Programme.

Content Approximate Time Needed

Is there help?Where can I find it?

Week #1

Homework 1 : Images 45 minutes Knowledge organiser,

bbc bitesize, youtbe, OCR revision books, Mr Frazer’s website

Week #2

Homework 2: Characters 45 minutes Knowledge organiser,


Week #3

Homework 3: Binary Representation 45 minutesConverting Denary to Binary bbc bitesize, youtbe, OCR revision

books, Mr Frazer’s websiteWeek #4

Homework 4: 45 minutes Converting Binary to Denary


Week #5

Homework 5: Wired & Wireless Network 45 minutesLAN vs WAN bbc bitesize, youtbe, OCR revision

books, Mr Frazer’s websiteWeek #6 -HalfTerm

Homework 6: Network Hardware 45 minutes Knowledge organiser


Week #7

Homework 7: 45 minutes Knowledge organiserExam style questions on Network/Internet


Week #8

Homework 8: The Internet 1hr Knowledge organiser& Packet switching bbc bitesize, youtbe, OCR

revision books, Mr Frazer’sWeek #9

Homework 10: System security & Network threats 45 minutesbbc bitesize, youtbe, OCR revision books, Mr Frazer’s website

Week #10

Homework 11: Secondary Storage 1hr


Week # 11

Homework 12: Logic gates 1hr


Images: Homework 1

Task 1 – Getting it!

1. This image uses four colours so requires 2 bits per pixel. Shade in the image as a computer using the key.

10 10 10 10 10 10 10 10 10 10 10 10 10 10

10 00 00 10 00 00 10 00 00 10 00 00 00 10

10 00 00 10 00 00 10 00 00 10 00 00 00 10

10 10 10 10 10 10 10 10 10 10 10 10 10 10

10 00 00 10 00 00 10 00 00 10 00 00 00 10

10 00 00 10 00 00 10 00 00 10 00 00 00 10

10 00 11 10 10 10 10 10 10 10 10 10 10 10

10 11 11 10 10 10 10 10 10 10 10 10 01 01

10 10 10 10 11 11 10 10 10 10 11 11 10 10

00 00 00 00 11 11 00 00 00 00 11 11 00 00

Key: 01 00 11 10

2. What is meant by the resolution of an image?

…………………………………………………………………………………………..

3.Describe how a black and white image could be represented in binary,

2[3]

[1]

Task 2 – Got it!

1. Describe what is meant by colour depth

2. How many bits per pixel (colour depth) would be required for an image with a palette of 256 possible colours?

3. Additional metadata data is stored alongside the binary colour values for each pixel. Give two examples of metadata.

Task 3 – Google Hire Me!

1. Calculate the file size of the following images:

Image Resoluti

on

Number of colours

Colour depth in

bits

File size in bits

File size in Bytes

Image 1 20 x 20 8

Image 2 10 x 10 8

Image 3 20 x 20 4

3

[6]

[1]

[2]

[1]

2. Which icon image is greater in file size? (Show your working)

a. A 256 colour icon with dimensions of 50 x 50 pixelsb. A 16 colour icon with dimensions of 100 x 100 pixels

4. State 2 factors that affect the file size of a bitmap image

5. Explain the relationship between image quality and file size

Characters: Homework 2Task 1 –

1. Write your initials in binary digits below using the ASCII table:

2. Using the 8-bit ASCII set, what would be the total size in bytes of the words ‘Computer Science’?

4

[2]

[2]

[2]

Total Marks [20]

[1]

[1]

3. What is meant by a character set?

4. Integers which are to be used in calculations are represented as pure binary numbers. (a) What is the pure binary representation of the number 76?

(b) The ASCII character 7 is represented by the denary number 55. Convert the ASCII string ‘76’ to binary.

Task 2 – Got It!

1. A simple three-letter code word is saved to a personal disk.

(a) What is the size in bytes of the code word?

(b) The code word is represented on the disk in a binary format, saved as:

01000011 01000001 01000010

Using the section of the ASCII table above, what is the code word? .

2. The eighth bit is used to give an extra 128 characters. Any character in the ASCII table can be typed using the ALT key in combination with its ASCII code.

For example, if you type ALT + 065 on the numeric keypad, the letter A will appear.

What is the binary representation of the letter A?

5

[1]

[1]

[1]

[1]

[1]

3. Typing ALT + 0233 will produce é.What is the binary representation of the letter é?

Task 3 – Google Hire Me!

1.How many characters can be represented with the 7-bit ASCII character set?

2. (a) What are the limitations of the 8-bit extended ASCII character set?

(b) How can these limitations be overcome?

3. The function ord(a) returns the denary value of the ASCII representation of the character a.

The function chr(i) returns the character whose ASCII code is the integer i .

The ASCII representation for A is 65 (denary).

What will be printed when the following program is run?

x = ord(‘C’)y = x + 3z = chr(y)print (x,y,z) …………………………………………………………………………………………………………

4. A programmer writes the following lines of code in Python. All data is input as ASCII characters.

6

[1]

[1]

[1]

[1]

[1]

[1]

print("Please input an integer x: ")x = input()print("Please input a second integer y:")y = input()z = x + yprint ("x + y = ", z)

The user enters 7 and 4. What will be printed? Explain your answer.

5. The programmer changes the second and fourth lines to readx = int(input())y = int(input())

The user enters 7 and 4. What will be printed?

6. The programmer changes the program to the following:

print("Please input an integer x: ")x = input()print("Please input a second integer y:")y = input()z = x - yprint ("x - y = ", z)

What will happen when the program is run? Why?

ASCII Codes

7

[2]

[1]

[1]

Decimal Binary Characte

rDecima

l Binary Character

Decimal Binary Characte

r

320010000

0space 64

01000000

@ 960110000

0'

330010000

1! 65

01000001

A 970110000

1a

340010001

0" 66

01000010

B 980110001

0b

350010001

1£ 67

01000011

C 990110001

1c

360010010

0$ 68

01000100

D 1000110010

0d

370010010

1% 69

01000101

E 1010110010

1e

380010011

0& 70

01000110

F 1020110011

0f

390010011

1' 71

01000111

G 1030110011

1g

400010100

0( 72

01001000

H 1040110100

0h

410010100

1) 73

01001001

I 1050110100

1i

420010101

0* 74

01001010

J 1060110101

0j

430010101

1+ 75

01001011

K 1070110101

1k

440010110

0, 76

01001100

L 1080110110

0l

450010110

1- 77

01001101

M 1090110110

1m

460010111

0. 78

01001110

N 1100110111

0n

470010111

1/ 79

01001111

O 1110110111

1o

480011000

00 80

01010000

P 1120111000

0p

490011000

11 81

01010001

Q 1130111000

1q

500011001

02 82

01010010

R 1140111001

0r

510011001

13 83

01010011

S 1150111001

1s

520011010

04 84

01010100

T 1160111010

0t

530011010

15 85

01010101

U 1170111010

1u

540011011

06 86

01010110

V 1180111011

0v

8

550011011

17 87

01010111

W 1190111011

1w

560011100

08 88

01011000

X 1200111100

0x

570011100

19 89

01011001

Y 1210111100

1y

580011101

0: 90

01011010

Z 1220111101

0z

590011101

1; 91

01011011

[ 1230111101

1{

600011110

0< 92

01011100

\ 1240111110

0|

610011110

1= 93

01011101

] 1250111110

1}

620011111

0> 94

01011110

^ 1260111111

0~

630011111

1? 95

01011111

_ 1270111111

1del

Binary Representation – Homework 3

Converting Denary to Binary Numbers

9

2.6 Data Representation

What is Binary? Why do computers use binary?

Complete the table below:

No of bits/bytes Common description of bits/bytesa 1 or a 0 (b)

1 nibble8 bits

1 Kilobyte (KB)1024 Kilobytes

1 Gigabyte (GB)1024 Gigabytes1024 Terabytes

Task 1 Denary = 6

Answer in binary

Calculation for answer

2 + 4 = 6

128 64 32 16 8 4 2 1

0 0 0 0 0 1 1 0

10

Task 2 Denary = 15

Answer in binary


128 64 32 16 8 4 2 1

Task 3 Denary = 21

Answer in binary


128 64 32 16 8 4 2 111

Task 4 Denary = 39

Answer in binary


128 64 32 16 8 4 2 1

Task 5 Denary = 54

Answer in binary


12

128 64 32 16 8 4 2 1

Task 6 Denary = 78

Answer in binary


128 64 32 16 8 4 2 1

Task 7 Denary = 99

Answer in binary

13


128 64 32 16 8 4 2 1

Task 8 Denary = 106

Answer in binary


128 64 32 16 8 4 2 1

Task 9 Denary = 180

Answer in binary

14


128 64 32 16 8 4 2 1

Task 10 Denary = 200

Answer in binary


128 64 32 16 8 4 2 1

Converting Binary to Denary Numbers: Homework 4Calculating a denary number from a binary number

15

Example 1: binary number = 00000011

128 64 32 16 8 4 2 1

0 0 0 0 0 0 1 1

0 0 0 0 0 0 2 1

Answer 2 + 1 = 3

Example 2: binary number = 00001011

128 64 32 16 8 4 2 1

0 0 0 0 1 0 1 1

0 0 0 0 8 0 2 1

Answer 8 + 2 + 1 = 11

Task 12: binary number = 00001111

128 64 32 16 8 4 2 1

0 0 0 0 1 1 1 1

16

Answer


128 64 32 16 8 4 2 1

0 0 1 0 1 0 1 0

Answer

Task 14

Write the formula in working out the binary numbers:

…………………………………………………………………………………………………………

Task 15

Explain why binary numbers known as machine codes

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………


128 64 32 16 8 4 2 1

0 1 0 1 1 0 1 1

17

Answer


128 64 32 16 8 4 2 1

Answer


128 64 32 16 8 4 2 1

Answer


128 64 32 16 8 4 2 1

18

Answer


128 64 32 16 8 4 2 1

Answer

Explain why binary number is base 2

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

Explain why denary number is base 10

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

Explain why Hexadecimal is base 16

………………………………………………………………………………………………….

Wired and Wireless Homework 5 Task 1: LAN vs WAN

19

Key point to research LAN WAN

How big is the area that this type of network covers? Geographically small? Geographically large?

How are computers normally connected together in this type of network Wired (Ethernet) Wirelessly Dedicated Lines Leased Line The Internet Satellite Phone Lines

What is the average speed of data transmission on this type of network? Kbps? Mbps? Gbps?

What kind of costs is involved in setting up this type of network? Initial purchase of hardware? On-going costs

(subscriptions)? Cable costs

How secure is this type of network? What security risks are

there? What could be done to help

the security?Can you give an example of this type of network?

Advantages of Networks:

20

Task 2 – Client Server vs Peer to PeerTick the correct box(es) to show whether the statement applies to a client-server, a peer-to-peer or both networks.

Statement Client-Server Peer-to-peer

Computers are networked together.

It has a central computer that provides all the services to the network.

Each computer in the network is equal, there is no central computer controlling services.

Most commonly found in a home or small office.

Most commonly found in larger offices and organisations.

Files can be automatically backed-up to a central location from each computer on the

network.

Peripherals on the network can be shared.

An expensive network to set up as more hardware needs to be purchased

A cheaper network to set up as less hardware needs to be purchased

Files can be shared using the network.

Each computer on the network needs to be maintained separately.

21

Task 3 – Performance of NetworksList the factors that could affect the performance of a network

Name the type of Network we use at home

…………………………………………………………………………………………………………………………….

Homework 6: Network Hardware: Task 1In order to connect to and set up a network you need the following hardware. Describe the role of each:

Wireless Access Point

Router/Switch

22

Network Interface Card (NIC)

Transmission Media

Task 2 – The CloudWhat is the Cloud?

Advantages Disadvantages

23

Task 3 – MatchingTerm Definition

Coaxial cable

The least expensive transmission media that consists of two wires that wrap around each other. Used as a standard (Ethernet)

RouterConnects together different networks and forwards data packets along a network.

Wireless access point

A transmission media that consist of a central wire, surrounded by insulation and a shield of braided wire to minimise interference.

SwitchA connection point for devices in a network. Unintelligent – packets are broadcast to every device.

Twisted pair cable

A device that allows other devices to connect to a network using standards such as Wi-Fi and Bluetooth.

Network interface card

A transmission media that consists of a bunch of glass or plastic threads.

Fibre optic cableA hardware device internal to a computer that allows a computer to connect to a network.

Hub Filters and forwards data packets within a single network. This creates a

24

Term Definition

direct connection between devices (intelligent)

Task 4 – Domain Name System and Hosting

What is a DNS Server?

What is Hosting?

What is meant by the Internet?

25

Exam Style Questions on Network/Internet: Homework 7

1. Tick a column to show whether the following statements are true or false: [2]

True False

The worldwide web is an example of client-server computing

A local area network may be configured as a client-server network

2. The diagram below shows the computers for a small accountancy firm connected together in a local area network.

(a) Does the diagram show peer-to-peer network or a client-server network?[1]

(b) What is the device A which connects to the Internet? [1]

26

Internet

Server

A

(c) Name three functions of the server in this network. [3]

(d) Name three advantages of linking computers in a small office in a peer-to-peer network. [3]

3. The accountancy firm uses a file hosting service in the Cloud to manage their files and data.

(a) Briefly describe what is meant by ‘The Cloud’ [2]

27

(b) Give two advantages to using cloud-based services over local storage. [2]

(c) Office staff notice that the network is running slowly compared to their home network connections.

Explain two factors that can affect network performance. [4]

(d) State two types of network transmission media. [2]

28

[Total 20 marks]

The Internet and Packet Switching

Homework 8

Task 1: The Internet - True False

The Internet is part of the World Wide Web

Each household in the UK has a unique IP address

The IP address of a laptop will change as you travel to different places

Every networked device in the world has a unique MAC (Media Access Control) address

To use the Internet, you must be connected to a router, either by cable or using a wireless connection

Task 2 – Star and Mesh TopologiesDraw and label diagrams for the 2 topologies

Star Mesh

29

Task 3 Wifi and Ethernet Ethernet

Frequency and Channels

30

Task 4 – Packet Switching

Packet = data sent between networks is split into smaller sized chunks called packets.

Contents of a Packet

Explain with the aid of a diagram the concept of a packet switching network.

Task 5 – ProtocolsProtocol Name Full Name What does it do? When would I use it?

TCP/IP

Transmission Control Protocol/Internet Protocol

Defines how data is sent and transmitted and received over the internet. Defines four ‘layers’ for the transmission of data.

31

Hyper Text Transfer Protocol

Hyper Text Transfer Protocol Secure

When accessing a webpage/website where you may want to encrypt data – e.g. a Bank website.

File Transfer Protocol

Allows the transfer of files between computers

POP

Another email protocol that us used to retrieve email from mail servers. This is a more recent protocol compared to POP.

SMTP

32

Task 6 - Layers

Layer Name Protocols in this layer Protocol Examples

IP

TCP

Ethernet

FTP

33

Systems Software – Homework 9

Systems Software = Software designed to maintain and control the hardware, it also provides and interface between software and hardware. The two main types of systems software are operating systems and utility programs

Operating system = controls the hardware and software/provides and interface for the user

Utility programs = help to maintain the computer

Task 1 – Operating System

What do you think an operating system does? Use the images to give you a few ideas.

34

Task 2 – Functions of an Operating System Notes:

a) Explain what is meant by memory management and multitasking and why it benefits the user: [4 marks]

b) Describe 2 other features of an operating system [4 marks]

c) What is meant by a peripheral and a driver? [2 marks]

35

Task 3 – Utility Software

Encryption

What it is =

Benefit =

Defragmentation

What it is =

Benefit =

Compression

What it is

Benefit =

Backup

What it is=

36

Benefit =

Full vs Incremental Backup

Full Incremental

Description

Advantages

Disadvantages

Systems Security – Homework 10

Network Threats Task 1 1. Look at the following text message. What action

should the recipient take?

37

Give reasons for your answer:

[2]

2. Do some research on Denial of Service attacks and write up your findings. Be sure to include answers to the following questions.

[5]• What is a DoS attack?• Who is typically targeted?• Who does it typically affect?• Is it always intentional?• How can it be countered?

…………………………………………………………………………………………………………………….

38

Total Marks 2

3. Study the email on the following page. Describe three clues which indicate that it is a phishing scam. [3]

Task 2: Identifying and Preventing Vulnerabilities

1. What might a company put in its own Acceptable use policy and why? [2]

2. Explain the purpose of penetration testing. [2]

39

Total Marks 8

3. List two items of information that you would expect an audit trail carried out by the computer department of an organisation to provide. [2]

4. Describe two measures that a school could take to ensure the security of the school network. [4]

Key Term Definition

Malware

Phishing

Brute Force

Denial of Service

Task 3: Key Words on Network security

40

Total Marks 10

State definition of each key word

41

Key Term Definition

Social Engineering

SQL Injection

Network Policy

Penetration Testing

Network Forensics

Firewalls

User Access Levels

Strong Password Features

Secondary Storage – Homework 11

Task 1

Optical Magnetic Solid State/Flash

Main Features of Operation:

Advantages:

Disadvantages:


Advantages:

Disadvantages:


Advantages:

Disadvantages:

42

Task 2:

For the devices listed below tick one bow to show which type of storage it is:

Task 3:Complete the table below using High, Medium or Low as appropriate for each storage medium. Some devices do not necessarily have a right or wrong!

Capacity Speed Portability

Durability

Reliability Cost

HDD

SSD

CD

DVD

Blu-RayUSB Flash Memory

43

Device Magnetic Optical Solid State

Hard Disk Drive

Solid State Drive

Blu-ray

DVD ROM

SD Card

USB Memory Stick

CD ROM

Tape Drive

Task 4: Calculating File Sizes

Estimate the following file sizes:

a) A text file that contains 10000 characters. Give your answer in KB

……………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………….

b) An image is 2030 x 1000 pixels in size. It has 65536 colours. Give your answer in GB.

……………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………….

c) A sound file has 4 bytes per sample. It takes 100 samples per second, over 1 channel and is 2 minutes 30 seconds long. Give your answer in KB.

……………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………

Logic Gates Workbook: Homework 12

Question 1

The diagram below is for a NOT gate. Complete the truth table for this gate.

44

Question 2

The diagram below is for an AND gate. Complete the truth table for this gate

A B Q

0 0 00 1

1 0

1 1

Question 3

The diagram below is for an OR gate. Complete the truth table for this gate.

A B Q45

¬A

A B

AvB

A Q

0 11

0 0 00 1

1 0

1 1

Question 4

Complete this table to show every possible combination of logic inputs for A and B

A B

0 0

Question 5

Complete this table to show every possible combination of logic inputs A, B and C

A B C

46

0 0 00 0 10 1 00 1

1

1

Question 6.

Logic gates can be combined to make a circuit.

You can use partial tables to help work out the complete truth table for the circuit.

The complete truth table only ever includes the actual inputs plus the final output but not the in-between points.

47

a) Fill out all possible values of B in the logic circuit shown above

A B

0 00 11

1

b) Complete the truth table for point P

A B P

0 0 00 1

1 0

48

1 1

c) Complete the truth table for Q given every value of P from above.

¬P Q

0

1

1

1

d) Now use the above tables to complete this truth table.

A B Q

0 0

0 1

1 0

1 1

Question 7

Complete the truth table for this circuit.

A B Q

0 0 0

49

0 1

1 0

1 1

Question 8

The logic circuit below has 3 inputs and so there are 8 possible combinations of A, B and C.

a) Complete the table below to show all the possible values of A, B and C

A B C

0 0 00 0 10 1 00 1 11

1

b) By using the table above, fill out the possible values of the OR gate

A B C A v B

0 0 0

0 0 1

50

0 1 0

0 1 1

1 0 0

1 0 1

1 1 0

1 1 1

Now work out every value of Q for the circuit

A B C A v B Q

0 0 0

0 0 1

0 1 0

0 1 1

1 0 0

1 0 1

1 1 0 0

1 1 1 1

51

Question 9

This logic circuit is for an AND gate.

This AND gate can be written as Q = A AND B

Now write down the equivalent statement for the OR gate for the logic circuit on the right

STATEMENT:

52

Question 10

Write down the logic statement for the gate shown below

STATEMENT:

Question 11

Logic gates can be combined to make more complicated circuits such as the one below.

53

Work out the logic statement for this circuit.

We have given you a few hints to start you off

Fill out the statement for P P = A OR .........

This is the statement for Q given P Q = NOT (P)

Now fill out the complete logic statement below

ThereforeQ = NOT ( A ........ B)

Write the statement replacing the words with the correct symbols

QUESTION 12

54

Complete the logic statements for this circuit

STATEMENT:

P = A .................

Q = NOT (.......)

Therefore

Q = NOT(........................)

Question 13

Complete the logic statement for this circuit

STATEMENT:

55

P = ...................

Q = P ............... B

Therefore the final statement is

Q = .......................................

Example

You can draw a logic circuit directly from a logic statement.

For example, the logic circuit for the statement Q = C AND (A OR B) looks like

Question 14

Draw the logic circuit for Q = C OR (A AND B)

56

Question 15

Draw the logic circuit for the statement Q = A AND (B OR C)

57

task 1 – getting it! - arkacton.org · web viewhomework 12: logic gates 1hr. bbc bitesize,...

Documents