The document discusses data representation in computers. It explains that: 1) Data is stored in binary form using bits, with the basic unit being a byte made up of 8 bits. Each byte can represent one character using ASCII codes. 2) When a user types a letter on a keyboard, it is converted to its ASCII binary code and stored in memory. This allows the letter to be processed and displayed on an output device. 3) Common units for measuring data size are kilobytes, megabytes, and gigabytes which are powers of 1024, 1024^2, and 1024^3 bytes respectively. Clock speed of a processor, measured in Hertz, determines how fast it can process data.

1. DATA REPRESENTATION Binary Number System Bit Byte Character ASCII

2. BINARY DIGIT Bit is smallest unit of data

3. 3 Binary Number System

4. 4 Binary Communication Between Hardware and Software

5. Step 1.The user presses the capital letter D (shift+D key) on the keyboard. Step 4.After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device. How is a letter converted to binary form and back? Step 2.An electronic signal for the capital letter D is sent to the system unit. Step 3.The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing.

6. BIT BIT stands for Binary Digit It is the smallest size of computer data storage It can either store a binary “0” or a “1” 0 1 OR Therefore a BIT can have 2 different values or combinations.

7. Byte – a group of 8 bits. Therefore, a byte can represent up to 28=256 values. The values can range from 0 to 255 or from -128 to 127. The fundamental data unit of a computer. ? ? ? ? ? ? ? ?

8. Data Representation 2 Presentation Unit 2 Slide 8 BYTE The 256 possible combinations are shown below:

9. Data Representation 9 Bytes as unsigned integers Base 2 number using positional notation 0 0 1 0 0 0 1 1 128 64 32 16 8 4 2 1 most significant bit least significant bit Value is 32 + 2 + 1 = 3310

10. CHARACTER 8 bits = 1 byte = 1 character (like ‘A’) One byte represent one character such as A, 7, 9 and @ For example the 01000110 represented a letter “F” 0 1 0 0 0 1 1 0 = F

11. ASCII

12. Example ‘a’ = 11000012

13. = = = = = = = = = = = = Binary 01001000 01100101 01101100 01101100 01101111 00101100 00100000 01110111 01100111 01110010 01101100 01100100 Decimal 72 101 108 108 111 44 32 119 103 114 108 100 H e l l o , w o r l d = = = = = = = = = = = = Note: 12 characters – requires 12 bytes Each character requires 1 byte “Hello, world” Example

14. DATA MEASUREMENT 1 KB = 210 bytes = 1024 1 MB = 220 bytes = 1048576 byte 1 GB = 230 bytes = 1073741824 1 TB = 240 bytes =1099511627776

15. CLOCK SPEED MEASUREMENT “SPEED” means how fast it can process data Every processor contains a system clock. The system clock control the speed of all operations within a computer. The clock speed unit is measured in Hertz. A Hertz is one cycle per second.

16. UNIT OF SPEED