1. Computer Structure & Architecture 7c - Data Representation

2. Lesson 5 – Representing Text LI:Describe how text is stored in a computer’s memory using the terms character set, ASCII and control characters

3. ASCII Character Set A character set is a collection of all the letters (upper and lower case), symbols, punctuation marks and numbers (not used in calculations) that can be represented and stored in computer memory. ASCII (American Standard Code for Information Interchange) is one example of a character set It can represent 128 (2 7 ) characters Each character has a unique 8 bit code (left-most bit is always 0 and used for error checking) The first 32 characters are non-printable characters which perform special functions such as RETURN, ESC, Backspace. These are known as Control Characters UNICODE is another example of a character set It can represent 65536 characters as it uses 16 bits It is used to represent non-Latin characters such as Arabic

4. Lesson 6 – Representing Numbers LI:Describe how integers are stored in a computer’s memory Convert decimal numbers to binary and vice versa

5. Representing Numbers Numbers are represented in computer’s memory as their binary equivalents. For example the 8 bit representation of the decimal integer 13 would be 00001101 When converting a binary number to decimal we write the binary number under its unit headings: 1286432168421 0001100100011001 Then where a 1 appears under a unit heading, add the unit headings together: 16+8+1 = 25

6. Representing Numbers When converting a decimal integer to binary we perform a simple division. e.g. The process of converting the number 47 would be: 1286432168421 0010111100101111 47/128 = 0 47/64 = 0 47/32 = 1 r15 15/16 = 0 15/8 = 1 r7 7/4 = 1 r3 3/2 = 1 r1 1/1 = 1

7. Lesson 7 – Advantages of Binary LI:Explain the key advantages of computers using binary

8. Advantages of Binary Binary is a simple two-state system (1 or 0) which is ideal when representing a two state system of power on/power off. There are only a few rules for addition, making calculations simpler (compared to decimal). A degraded signal can still be detected as representing 1 or 0. e.g. Degraded Signal…can be still be read as…