1. National 5 Computer
Science
Software Development
Faculty of ICT

2. Aims - Systems Lesson 1
 To
introduce Course Structure
 Issue Jotters/Resources
 Rules
 5 Box Diagram
 Discuss Hardware/Software/Input/Output
Device
 Create Folder label

3. Class Rules
1.
2.
3.
4.
5.
6.
7.
8.
9.
Get to class on time and line up quietly with jacket off
Come into class in an orderly fashion and take out folder
No chewing gum!!!!!!!!!!!!!!!!!!!!!!!!
Always sit at the “Theory desks” to see lesson aims
Take out pencil/pen
No talking when I am talking!!!!!!!!!!!!!!!!!!!!!!!!
Hands up when answering
Treat others in class with respect
Follow all instructions

4. Course Outline
 Mandatory


Units
Software Design and Development (3 outcomes)
Information Systems Design and Development (2
outcomes)
 Evidence
should be gathered throughout the
year to meet the 5 outcomes
 Assessment


Written Exam 90 marks
Coursework in class 60 marks

5. Folders to Create
 S4


Computer Science
Software Development
Info Systems Design and Development

6. 5 Box Diagram

7. Aims - Systems Lesson 2
Last Lesson
 5 Box Diagram
 Hardware/Software/In
put/Output Device
 Folder label
Today
 Main Memory



RAM
ROM
Create poster on
Hardware/Software/R
AM and ROM

8. Main Memory
 Main
Memory can either be RAM or
ROM
 Random Access Memory




RAM holds all the data currently in use by
the Computer System
Volatile = the contents are lost when the
Computer is Switched off
Processor can read and write to RAM at
high speed
Typically 4-8Gb in a Desktop

9. Main Memory
 Read


Only Memory
Data is stored permanently and cannot be
changed
Data is written to ROM at manufacture

10. Lesson Starter
1.
2.
3.
Give 3 examples of Input Devices
What does RAM and ROM stand for?
What is the difference between RAM and
ROM?

11. Aims - Systems Lesson 3
Last Lesson
 Main Memory



RAM
ROM
Hardware Poster
Today
 The Processor


ALU/Control Unit
Find 4 devices and
take a note of their
Processor Speed

12. The Processor
The processor or Central Processing Unit is the
brain of the computer where all the decision
making, calculations etc are carried out
 We send instructions (programs) to the processor
to get the computer to do something
 Processor speed (clock speed) is measure in how
many millions of instructions the processor can
process per second (typically 3-4Ghz)
 Dual Core = 2 processors
 Quad Core = 4 processors


13. Parts of the Processor
 Control


Unit
Makes sure programs are processed in
the correct order
Is responsible for bringing data from
RAM into the processor
 Arithmetic


Logic Unit
Performs calculations
Makes decisions using AND, OR, NOT
and IF

14. Registers
 Registers
are storage locations inside the
processor
 Memory Address Register

These Registers store the addresses of where the
data came from in RAM
 Memory

Data Register
These store the data that has been read from
RAM or going to be written back to RAM

15. Backing Storage


A Backing Storage device is a 
piece of hardware that is used
to store data permanently when
the computer is switched off

Magnetic




Hard Disk (500Gb – 1TB)
Magnetic Tape (500TB +)
USB Memory Stick (2GB- 64Gb)
Optical





CDROM/R/RW (750Mb)
ROM = written at manufacture
Recordable = store to once then ROM
Rewriteable = save over the top of items
DVDROM/R/RW (4.7Gb)
Sequential Access = This
is Backing Storage where
you access data in a
particular order
Direct Access = This
Backing Storage allows
you to access data in any
order

16. Interface
An interface is a piece of hardware
positioned between a peripheral and
the CPU. The interface
compensates for any differences
 USB
 Firewire
 Functions




The interface compensates for the
difference in speed
Analogue to Digital Conversion
(Microphone – Processor)
Interface may temporarily store data,
for example, the buffer in the printer

17. Aims - Systems Lesson 4
Last Lesson
 The Processor
 ALU/Control Unit
Today
 The Processor

Registers
Address Bus
 Revision Questions


18. Processor

19. Buses
 Buses
are wires or channels that carry data
to and from the Processor and Main Memory
 Address Bus



Carries Address information from RAM into the
Memory Address Register in the Processor
1 way
The larger the address bus the more addresses
you can access

20. Buses
 Data




Bus
Carries data to and from RAM into the Memory
Data Register
2 way
The number of wires in the Data Bus determines
how much data can flow per clock cycle
The width of the Data Bus directly affects
performance

21. Aims - Systems Lesson 5
Last Lesson
 The Processor


Registers
Address Bus
Today
 Data Bus
 Interfaces

22. Aims - Systems Lesson 6
Last Lesson
 Data Bus
 Interfaces
Today
 Data Storage
 Storage Units
 Storage Calculations

23. Data Storage


Numbers, Text,
Images, Sound and
video are all stored as
a series of ons and offs
(1s and 0s) inside the
computer system.
These series of 1s and
0s are made up of
pulses of electricity
from 1 volt to 5 volts

24. Storage Capacities
0 or 1 = 1 bit
8 bits = 1 byte
1024 bytes = 1 Kilobyte
1024 Kilobytes = 1 Megabyte
1024 Megabytes = 1 Gigabyte
1024 Gigabytes = 1 Terabyte

25. Storage of Music Files





William has an Ipod with a capacity of 1Gigabyte (1Gb). If a song
requires 2 Megabytes of storage space, how many songs can
you store on the Ipod
1Gb = 1024Mb
Ipod = 1024Mb
Song = 2 Megabytes
Number of songs = 1024
2
=
512 songs

26. Storage of Music Files

Drew has an Ipad with a capacity of 32Gigabyte.
If an image requires 512 Kilobytes of storage
space, how many images can you store on the
Ipad?

27. Lesson Starter
 How
many 4Mb images can you store on an
8Gb Iphone?

28. Aims - Systems Lesson 7
Last Lesson
 Data Storage
 Storage Units
 Storage Calculations
Today
 Representing positive
whole numbers


Decimal to Binary
Binary to Decimal

29. Decimal Counting System
When we represent numbers we use the decimal
counting system, for example
 123,000
100,000
10,000
1,000
100 10
1
1
2
3
0
0
0
 Since the computer is 2 state, the binary counting
system goes up by the power 2, rather than 10 i.e
256 128 64
32
16
8
4
2
1


30. How Positive Whole Numbers are
Stored
34
128 64 32
0
0
1
= 32 + 2
 134
128 64 32
1
0
0
= 128 + 4 + 2

16
0
8
0
4
0
2
1
1
0
16
0
8
0
4
1
2
1
1
0

31. Binary back to Decimal
1011 0011
128 64
32
16
8
1
0
1
1
0
= 128 + 32 + 16 + 2 + 1
=179
4
0
2
1
1
1

32. Binary Conversion
Convert the following
Decimal Numbers to
Binary
 31
 67
 105

Convert the following
Binary Numbers to
Decimal
1011 0111
0011 0110
0101 1011


33. Aims - Systems Lesson 8
Last Lesson
Today
 Representing positive  Representing decimal
whole numbers
numbers using
 Decimal to Binary
Floating Point

Binary to Decimal

34. Representing Non Whole
Numbers
 How
do we represent the number 128.75 in
binary?
128
64
32
16
1
0
0
0
 128
8
0
4
2
0
+ 0.5 + 0.25
 = 128.75
1
0
0.5
0
1
0.25
0.125
1
0
0.0625
0

35. Mantissa and Exponent
128
64
32
16
8
4
2
1
0.5
0.25
0.125
0.0625
1
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
1
1
0
0
 Mantissa
1
0
0
 Exponent
8
8 4 2
1 0 0
1
0

36. How do we represent the number 38.125 using
floating point
32
16
8
4
2
1
0.5
0.25
0.125
0.0625
1
0
0
1
1
0
0
0
1
0
1
1
0
0
0
1
 Mantissa
1
0
0
 Exponent
6
8 4 2
0 1 1
1
0
0

37. Representing Non Whole
Numbers
 Mantissa
relates to the precision of the
number you can represent i.e 34.44454321
8
4
2
1
 Exponent
0.5
0.25
0.125
0.075
0.0375
0.01875
0.009375
relates to the position of the
decimal point and the range of the number

38. Aims - Systems Lesson 9
Last Lesson
Today
 Representing decimal  Representing
numbers using
characters
Floating Point
 ASCII

Unicode

39. How are Characters
Represented

ASCII




Character Set


American Standard Code for
Information Interchange
Each key on the keyboard is
converted into a binary code
using 7 bits
7
Using 7 bits i.e 2 = 128
characters can be represented
A list of all the characters
which the computer can
process
Control Characters

Codes 0 to 31 are non
printable characters, for
example tab, return, alt
Character Binary
Decimal
tab
000 1001
9
return
000 1101
13
space
010 0000
32
!
010 0001
33
‘
010 0010
34
1
011 0001
49
A
100 0001
65
a
110 0001
97

40. Unicode
 Unicode
is coding system which uses 16 bits
per character
16
 This allows 2 ^
characters
 65,536 characters can be represented
 Adv

Allows you to represent characters from different
languages
 Dis
 Takes
up more than double the space to
store each character

41. Binary Message
1010100
0100000
1010100
0100000
1001000
1001001
1001000
1010111
1001000
1001001
1001111
1000010
1001001
1000101
1000101
1010011
1010010
1001100
1010011
1000001
1010010
0100000
1010010
1000101

42. Lesson Starter
1.
2.
3.
4.
How many characters can be represented in
ASCII?
Give 1 advantage and 1 disadvantage of
Unicode over ASCII
Convert 129 to binary
What 2 items are stored in Floating Point?

43. Aims - Systems Lesson 10
Last Lesson
 Representing
characters


ASCII
Unicode
Today
 Representing Bitmap
images
 Pixels and Resolution

44. BIT Map Graphics
SCREEN
MEMORY
PIXEL
Bit Map = the graphic is made up
from a series of pixels
MEMORY REQUIRED
8 BITS X 8 BITS = 64 BITS
= 8 BYTES

45. Pixels/Resolution
 Pixel


Stands for Picture Element
A pixel is a dot on the screen. It is a graphic
segmented up into its simplest form

46. Graphics Resolution



The more pixels there
are per inch, the finer
the detail of the image
800 x 600 pixels lower
quality than 1024 x 768
As the number of pixels
increases so does the
storage space required
Pixel Pattern
using 8x8 grid
Pixel Pattern
using 16x16
grid

47. Aims - Systems Lesson 11
Last Lesson
 Representing Bitmap
images
 Pixels and Resolution
Today
 Bitmap Calculations
 Vector Images
 Revision on Systems
theory for end of Unit
Test

48. Bitmap Calculations
I
have a black and white image that is 400
pixels by 200 pixels. Calculate the storage
requirements of this image to the nearest kb
 I have a black and white image that is 600
pixels by 500 pixels. Calculate the storage
requirements of this image to the nearest kb
 I have a black and white image that is 4
inches by 3 inches with a Resolution of
400dpi. Calculate the storage requirements of
this image to the nearest kb

49. Bitmap Graphics
 In
a Bitmap package, each pixel is converted
into a series of on and offs 1/0.
 Images cannot overlap, the one on top
replaces the pixels below
 You can edit each individual pixel, for
example, red eye removal
 Gets very pixelated if you scale it up

50. Vector Graphics
 In
a Vector graphics
package , the image
is made up of shapes
layered on top of each
other
 The Object attributes
are stored

Shape = circle, startX,
startY, endX, endY,
circle colour, line
thickness

51. Aims - Systems Lesson 12
Last Lesson
 Representing Bitmap
images
 Pixels and Resolution
 Bitmap Calculations
 Vector Images
Today
 Colour Depth
 Compression

52. Bit Depth (Colour Depth)




The number of colours you use per pixel
The lower the bit depth = the less colours you
can represent per pixel, this would make the
image poorer quality
Reducing the colour depth reduces the file
size of the Bitmap image
The number of bits used to represent colours
in the graphic






1 bit = black or white
2 bits = 4 colours
3 bits = 8 colours
8 bits = 256 colours
16 bits = 65,536 colours
True colour 24 bits = 16,777,216 colours this is true
colour

53. Compression
 RAW

This is uncompressed data
 Compression


Where you reduce the file size of an image/ audio file etc
The file will take up less space on Backing Storage,
upload and download faster but some of the quality may
be lost
 Lossy

Compression where some of the original data is lost e.g
a JPEG
 Lossless

Compression where the file size is reduced but none of
the data is lost, e.g GIF

54. Quiz
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Which bus is unidirectional? (1)
List the 3 parts of the processor (3)
What is the difference between RAM and ROM? (1)
Convert 99 to binary (1)
What is the difference between a Bitmap image and a Vector
image? (1)
How many bits are used per character in ASCII and Unicode? (2)
What is the bitdepth of the image if it is in 65,536 colours? (1)
I have an image that is 700 pixels by 400 pixels in True Colour.
Calculate the storage requirements of the image (2)
What is the difference between Lossy and Lossless
compression? (2)
When storing a real number using Floating Point, what 2 items
are stored? (2)

55. Aims - Systems Lesson 13
Last Lesson
 Colour Depth
 Compression
Today
 File Formats
 Audio Sampling

56. Audio Sampling

57. Standard File Formats






A Standard File Format is a file format that will open up in many
different programs
Text
 TXT = the text is stored but none of the formatting is store
 Rich Text Format = the text and the formatting is stores, e.g. font
style, size etc
Audio
 MP3/WAV
Image
 GIF /PNG (lossless)
 JPEG (lossy)
 Bitmap = stores the colour for each pixel = very large file sizes
Video
 AVI/MOV/MPEG4
PDF = an Adobe file format for sharing documents. You cannot edit
the text in a PDF, only view it

58. Aims - Systems Lesson 12
Last Lesson
 Bitmap Calculations
 Vector Images
Today
 Systems End of Unit
Test

59. Aims – Software Development
Lesson 1
Today
 Variables
 Variable types
 Creating Variables
 Assigning Data to Variables

60. Variables



A variable is an item of data that is given a name and data type
and is stored in the computers memory for later use in a
program
Variables can be used to store a variety of different types of data
Variable Types





String = storing text e.g. “Mr HRH” or 01698_420437
Integers = whole numbers e.g. 232
Single = non whole (real) numbers e.g. 34.565
Booleans = storing a yes/no (true/false) value
Characters = stores a single Character e.g. A

61. Assigning Data to Variables
 Creating


Variables
Dim username as string (This will set up a
variable called username to store text)
Dim height as single (This will set up a
variable called height to store a decimal
number)
 Assigning

Data to Variables
username = inputbox(“Please enter your
username”) – This will bring up an input
box asking the user to enter a value and
will store it in the variable “username”

62. Lesson Starter
1.
2.
What is a variable?
Give 3 different variable types

63. Aims – Software Development
Lesson 2
Last Lesson
 Variables
 Variable types
 Creating Variables
 Assigning Data to
Variables
Today
 Arithmetic Operators
 String Manipulation

64. Arithmetic Operators
Remember when you are assigning data to
variables you start with the variable name you are
writing to first
area = length * breadth
area = 3.14 * (radius * radius)
answer = numberone / numbertwo
answer = numberone ^ 2

65. String Manipulation
 Concatenation


Joining together strings
username = forename & surname
 Substrings



Username = left(forename, 3) & right(surname,3)
If your forename = freddie and surname =
mercury this would give you freury
Left and Right are predefined functions

66. Lesson Starter
1.
2.
3.
I have the variables area, length and
breadth. Write the code to calculate the
area, using the other variables
I have the variables username, firstname
and surname. Write the code that would add
the first 4 characters from firstname to the
last 4 characters in surname, putting this
into the variable username
What is meant by string concatenation?

67. Aims – Software Development
Lesson 3
Last Lesson
 Arithmetic Operators
 String Manipulation
Today
 Conditional
Statements
 Logical Operators

68. Conditional Statements
 We
use Conditional Statements in
programming to make decisions
 If statements
If userage < 17 then
picDisplay.print “Cannot Drive”
Else
picDisplay.print “Can Drive”
End if

69. Logical Operators
 Using
AND, OR and Not as part of decision
statements
 AND = when both parts of the condition must
be met for the outcome to happen
If firstname = “Henry” AND surname = “Haggarty” then
outcome = “legend”
End if
 OR
= when 1 part of the condition must be
met for the outcome to happen
If team = “Celtic” OR team = “Rangers” then
supporter = “idiot”
End if

70. Aims – Software Development
Lesson 4
Last Lesson
 Conditional
Statements
 Logical Operators
Today
 Loops


Fixed
Conditional

71. Loops
A Loop is used to repeat instructions
 Fixed Loop


A fixed loop repeats the code a set number of
times
For num = 1 to 10
picDisplay.print “I must not swear”
Next num

72. Conditional Loops
 Input
Validation is a Standard Algorithm that
is used to ensure the data entered is within a
particular range
1.1 Loop while the number is less than 1 or more than 20
Do while entry < 1 or entry > 20
1.2 Ask the user to enter again
Entry = inputbox(“This is not valid, please enter again”
1.3 Close validation
loop

73. Nested Loop
A
loop inside a loop
For num = 1 to 5
rating(num) = inputbox(“Enter movie rating”)
Do while rating(num) < 0 or rating(num) > 5
rating(num) = inputbox(“Not valid”)
Loop
Next num

74. Conditional Loops
Loop Until
‘1.1 Open conditional loop
Do
‘1.2 Ask user to enter question
question = inputbox(“Enter question”)
‘1.3 Loop until they say please
Loop until question = “crisps please”

75. Aims – Software Development
Lesson 6
Last Lesson
 Nested Loops
 Input Validation
Today
 Predefined Functions
 1 Dimensional Arrays

76. Testing





When you test your program you should use 3
types of test data
Example = this program wants you to enter the
first number in the National Lottery (1 to 49)
Normal = data within the range (30 or 25 or 3)
Extreme = data at the boundaries of the normal
range (1 or 49)
Exceptional = data outside the normal range (50,
231 etc)

77. Readability of Code
 Someone
else looking at or editing your code
will understand it better if you do the following
 Internal Commentary



Each line of code should have a clear comment
1.1. Ask the user for this firstname
firstname = inputbox(“Please enter your first
name”)
 Meaningful



Variable Names
Dim username as string
NOT – dim u as string
This helps you identify exactly what you are
storing in your program

78. Readability of Code
 Indentation
For loopcounter = 1 to 5
picDisplay.print “Hello World”
Next loopcounter
If surname = “Arthur” then
picDisplay.print “Hello Mr Arthur”
End if
 The
start and end of your loops or If
statements should be aligned vertically so
you can see where they start and end

79. Design Notations
 In
the Design phase the problem is broken
down into chunks
 The solution to the problem is called the
Algorithm
 Stepwise Refinement = breaking the problem
down into smaller and smaller steps


Graphical Design Notations
Pseudocode

80. Text Based Design Notation
 Pseudocode

Where the stages of the program are broken
down and written in English steps

81. Lesson Starter
1.
2.
3.
Give 3 ways that you can improve the
Readability of a program
I write a program to calculate how many
yawns Jannat has per day. The program
should take in a value between 0 and 40.
Give 3 tests you could carry out on this
program, listing the test data
What design notation do you currently use to
break problems down into simpler steps

82. Graphical Design Notations
 Flow

Charts
These use different shaped
boxes to represent
programming elements



Diamonds = if statements
Rounded rectangles = loops
Rectangles = calculations

83. Case Diagram
 This
gives a quick overview of how a
program or system works
 This is a Case Diagram for a Customer
Order System

84. Activity Diagrams
 More
complex flow chart
 B = start or end of an activity
 Black circle represent the final state

85. Predefined Functions
 This
is a piece of code that has been
prewritten and you refer to it using a keyword
 Predefined functions only return 1 value
 Examples
 ucase (makes all the characters capital)
 round (this rounds the decimal number to the
nearest whole number)
 format(depth,”##.00”)
 username = left(firstname,3) – This takes the
first 3 characters from the variable username

86. Aims – Software Development
Lesson 7
Last Lesson
 Predefined Functions
 1 Dimensional Arrays
Today
 Filling Arrays with For
Loops
 Testing

87. 1 Dimensional Arrays
 Where
you store a list of data of the same
data type
 Dim username(100) as string
 This would set up an array to store 100
usernames
 Each element of the array is identified by the
variable name and index number



username(0) = “arod”
username(1) = “jdog”
username(2) = “eman”
 Option
Base 1
 This makes the array start at index 1

88. Arrays
Filling Arrays
For num = 1 to 100
Username(num) = inputbox(“Enter username”)
Next num
Displaying Arrays
For num = 1 to 100
picDisplay.print Username(num)
Next num

89. Lesson Starter

90. Lesson Starter

92. Errors in Code
 Syntax


Error
An error in the sequence of characters in your code
picDisplay.pritn (“Hello World”)
 Execution

Error
An error that prevents a program from running for
example, trying to assign to a variable that has not
been declared
 Logic
Error
An error in the design of the program that will result
in the wrong answer or output
If age > 60 or age < 100 then
picDisplay.print “Pensioner”


93. Aims – Software Development
Lesson 8
Last Lesson
 Filling Arrays with For
Loops
 Testing
Today
 Errors in Code
 Readability

96. High Level Languages
A
High Level Language is a programming
language that uses everyday words
 Features




English like words
Build in functions like left, right, mid, ucase
Must be translated to machine code
Portable - Can be run on different platforms
picDisplay.print “HRH is a legend”

97. Low Level Language Machine
Code
 Machine
Code is the only language a
computer can process
 101010101
 It is an impossible language to program in
and errors would be inevitable

98. Translators
All programs written in a
High Level Language
must be translated to
Machine Code
 Interpreters




Translates and executes
the program one line at a
time
Errors are highlighted at
each line making them
easier to identify
Interpreter is loaded into
RAM during translation

Compilers


Translates the High
Level Language
(Source Code) into
Machine Code (Object
Code) in one operation
You can run the Object
Code without the
Translator being
present in RAM

101. Counting Occurrences
5.1 Set the Counter to 0
5.2 Loop round for all the positions in the array
5.3 If the current position is the Target Value
5.4 Add 1 to Counter
5.5 End If
5.6 End loop

102. Finding Maximum
3.1 Set the lowest place in the array to maximum
3.2 Loop For the size of the array
3.3 If the current score is higher than maximum then set to maximum
3.4 End if
3.5 End Loop

103. Linear Search
4.1 Ask user for the target value
4.2 loop for each item in the list
4.3 If current item = target value then
4.4 Display target value
4.5 End if
4.6 End loop

104. Arrangements

105. Arrangements