Computer Systems Nat 45 Computing Science Data Representation

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Computer Systems Nat 4/5 Computing Science Data Representation Lesson 3: Storing Text

Computer Systems Nat 4/5 Computing Science Data Representation Lesson 3: Storing Text

REV ISIO N 1. What is the system used to store real numbers? 2.

REV ISIO N 1. What is the system used to store real numbers? 2. Convert 1100 into a decimal number 3. Convert 23 into binary. 4. Describe what is mean by a mantissa and exponent

1. ANS WER S Floating Point representation 2. 1100 = 204 3. 23 =

1. ANS WER S Floating Point representation 2. 1100 = 204 3. 23 = 0001 0111 4. In the number 3. 0 x 108 the mantissa would be 3. 0 with the exponent being 8

Lesson Aims By the end of this lesson you will be able to: Describe

Lesson Aims By the end of this lesson you will be able to: Describe how text is stored by the computer. Explain and give an example of an ASCII character. Describe how many bytes are needed to represent a single character of text. Describe what is meant by the term character set. Give an example of why we need different character sets.

Nat 4/5 A question… Computers can only use and understand binary digits which are

Nat 4/5 A question… Computers can only use and understand binary digits which are 0’s and 1’s. We have already looked at how binary can be used to store numbers. How By can we store text? storing them as binary numbers….

Nat 4/5 ASCII Codes Each character on a keyboard has its own ASCII code.

Nat 4/5 ASCII Codes Each character on a keyboard has its own ASCII code. This is a binary value that represents each character that can be seen on the screen. American Standard Code for Information Interchange For example A = 0100 0001 (65) Each ASCII value takes up 1 byte of storage.

Nat 4/5 ASCII Table An extract of the ASCII Table is shown below: The

Nat 4/5 ASCII Table An extract of the ASCII Table is shown below: The ASCII table has 128 values 52 just for text. 10 for numbers Spacebar and tab key have codes too What about the rest? Code Symbol 48 0 78 N 64 @ 97 a 49 1 79 O 65 A 98 b 50 2 80 P 66 B 99 c 51 3 81 Q 67 C 100 d 52 4 82 R 68 D 101 e 53 5 83 S 69 E 102 f

Nat 4/5 Control Characters The rest of the ASCII code are reserved for control

Nat 4/5 Control Characters The rest of the ASCII code are reserved for control characters. These are non-printable characters that have an effect such as The Enter key What about the trusted delete/backspace keys?

Nat 4/5 Character Set The character set is the name given to the complete

Nat 4/5 Character Set The character set is the name given to the complete set of characters that the computer can represent. Different character sets are used to represent different languages The character set can alter the layout of the keyboard For example on American layout keyboards the @ sign is above the number 2 not the “ mark.

Nat 4/5 Summary Text is stored in the computer using ASCII values 1 ASCII

Nat 4/5 Summary Text is stored in the computer using ASCII values 1 ASCII Value = 1 byte of memory Control characters are the non-printable characters which have an effect on the screen Such The as the Enter Key character set is the name given to the entire set of characters that the keyboard can produce

Network Address Translation NAT 1 NAT NAT deviceNetwork Address Translation NAT 1 NAT NAT device
NAT Network Address Translation NAT 64 NAT 6NAT Network Address Translation NAT 64 NAT 6
Nat Turner 1831 Nat Turner Why was NatNat Turner 1831 Nat Turner Why was Nat
Nat Int Nat Int nat 2 int ZeroNat Int Nat Int nat 2 int Zero
Nat Int Nat Int nat 2 int ZeroNat Int Nat Int nat 2 int Zero
Nat Int Nat Int nat 2 int ZeroNat Int Nat Int nat 2 int Zero
Computer Systems Nat 45 Computing Science Computer StructureComputer Systems Nat 45 Computing Science Computer Structure
Computer Systems Nat 4 5 Computing Science DataComputer Systems Nat 4 5 Computing Science Data
Computer Systems Nat 45 Data Representation Lesson 4Computer Systems Nat 45 Data Representation Lesson 4