Int 2 Computing

Mr Arthur

Course Outline

3 Main Units Computer Systems = 40 hours Software Development = 40 hours Artificial Intelligence = 40 hours

Assessment 3 End of Unit Assessments (NABS /20) 2 Practical Coursework Tasks (/15 - 30%) Written Exam (/70 or 70%)

Computer Systems

5 units in the Computer Systems Section1. Data Representation = 6 hours

2. Computer Structure = 7 hours

3. Peripherals = 5 hours

4. Networking = 9 hours

5. Computer Software = 9 hours

Aims of Lesson 1

1. How are numbers, text and images represented inside the computer system?

2. Discussing the 2 state computer system

3. Converting positive whole numbers to binary and vice versa

4. Playing Binary Bingo

Data Representation

100 billion switches per sq. cm

Data Storage

Numbers, Text, and Images are all stored as a series of 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

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

How Positive Whole Numbers are Stored

34

128 64 32 16 8 4 2 1

0 0 1 0 0 0 1 0

= 32 + 2 134

128 64 32 16 8 4 2 1

1 0 0 0 0 1 1 0

= 128 + 4 + 2

Binary back to Decimal

1011 0011

128 64 32 16 8 4 2 1

1 0 1 1 0 0 1 1

= 128 + 32 + 16 + 2 + 1

=179

Binary Bingo 42 81 21 16 121 73 101 75 127 128

13 209 32 56 175 192 186 176 121 250 34

Aims of Lesson 2

1. Data Units1. Bits/Bytes etc

2. Floating Point Representation

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

Representing Non Whole Numbers

How do we represent the number 128.75 in binary?

128 + 0.5 + 0.25 = 128.75

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

Mantissa and Exponent

Mantissa

Exponent

8

8 4 2 1

1 0 0 0

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

1 0 0 0 0 0 0 0 1 1 0 0

Mantissa

Exponent

6

8 4 2 1

0 1 1 0

1 0 0 1 1 0 0 0 1 0

1 0 0 1 1 0 0 0 1 0

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

Representing Non Whole Numbers

Mantissa relates to the precision of the number you can represent i.e 34.44454321

Exponent relates to the position of the decimal point

8 4 2 1 0.5 0.25 0.125 0.075 0.0375 0.01875 0.009375

Aims of Lesson 3

1. Representing Graphics1. Pixels

2. Resolution

2. Graphics Calculations

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 Resolution

This is the numbers of pixels there are per inch (dpi)

The higher the resolution the higher the quality of the image

BIT Map GraphicsSCREEN MEMORY

PIXEL

MEMORY REQUIRED

8 BITS X 8 BITS = 64 BITS

= 8 BYTES

Bit Map = the graphic is made up from a series of pixels

Graphics Resolution

The smaller the size of the pixels, 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

Calculating Storage Capacities of Bit Mapped Images

Storage Requirements = total number of pixels * number of bits used for each pixel

This picture of Mr Haggarty has a resolution of 300dpi. The image is 2 inches by 4 inches in 128 colours

300 X 2 = width 600 pixels

300 X 4 = height 1200 pixels

Total pixels = 600 X 1200 = 720,000 pixels

Each pixel = 7 bits i.e. 2 = 128 colours

720,000 X 7 = 5,040,000 bits / 8 = 630,000 bytes

630,000 / 1024 = 615Kb

7

Aims of Lesson 4

Last Lessons

1. Representing whole numbers

Decimal to Binary Binary to Decimal

2. Non-whole numbers Floating Point

3. Data Units

4. Representing Graphics1. Pixels

2. Resolution

5. Graphics Calculations

Today’s Lesson 1. Representing Text2. Advantages of using binary

How is Text Represented ASCII

Each key on the keyboard is converted into a binary code using 7 bits

Using 7 bits i.e 2 = 128 characters can be represented

Character Set 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

7

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

Binary Message

1010100 1001000 1001001 1010011

0100000 1010111 1000101 1000001

1010100 1001000 1000101 1010010

0100000 1001001 1010011 0100000

1001000 1001111 1010010 1010010

1001001 1000010 1001100 1000101

Advantages of Using Binary

Computers are 2 state e.g. on and off and Binary is a 2 state counting system e.g. 1010

If there is any drop in voltage (degradation) the pixel etc is still represented as a 1 (black)