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# Data representation

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### Data representation

1. 1. DATA REPRESENTATION<br />Binary Number System<br />Bit<br />Byte<br />Character<br />ASCII<br />
2. 2. BINARY DIGIT<br />Bit is smallest unit of data<br />
3. 3. 3<br />Binary Number System<br />
4. 4. 4<br />Binary Communication Between Hardware and Software<br />
5. 5. Step 1.The user presses the capital letter D (shift+D key) on the keyboard.<br />Step 4.After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.<br />How is a letter converted to binary form and back?<br />Step 2.An electronic signal for the capital letter D is sent to the system unit.<br />Step 3.The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing.<br />
6. 6. BIT<br />BIT stands for Binary Digit<br />It is the smallest size of computer data storage<br />It can either store a binary “0” or a “1”<br />0<br />1<br />OR<br />Therefore a BIT can have 2 different values or combinations.<br />
7. 7. Byte<br /> – a group of 8 bits. <br />Therefore, a byte can represent up to 28=256 values.<br />The values can range from 0 to 255 or from -128 to 127.<br />The fundamental data unit of a computer.<br />?<br />?<br />?<br />?<br />?<br />?<br />?<br />?<br />
8. 8. Data Representation 2 Presentation Unit 2<br />Slide 8<br />BYTE<br />The 256 possible combinations are shown below:<br />
9. 9. Data Representation<br />9<br />Bytes as unsigned integers<br />Base 2 number using positional notation<br />0<br />0<br />1<br />0<br />0<br />0<br />1<br />1<br />128 64 32 16 8 4 2 1<br />most<br />significant<br />bit<br />least<br />significant<br />bit<br />Value is 32 + 2 + 1 = 3310<br />
10. 10. CHARACTER<br />8 bits = 1 byte = 1 character (like ‘A’)<br />One byte represent one character such as A, 7, 9 and @<br />For example the 01000110 represented a letter “F”<br />0<br />1<br />0<br />0<br />0<br />1<br />1<br />0<br />=<br />F<br />
11. 11. ASCII<br />
12. 12. Example ‘a’ = 11000012<br />
13. 13. =<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />Binary<br />01001000<br />01100101<br />01101100<br />01101100<br />01101111<br />00101100<br />00100000<br />01110111<br />01100111<br />01110010<br />01101100<br />01100100<br />Decimal<br />72<br />101<br />108<br />108<br />111<br />44<br />32<br />119<br />103<br />114<br />108<br />100<br />H<br />e<br />l<br />l<br />o<br />,<br />w<br />o<br />r<br />l<br />d<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />=<br />Note: 12 characters – requires 12 bytes<br />Each character requires 1 byte<br />“Hello, world” Example<br />
14. 14. DATA MEASUREMENT<br />1 KB = 210 bytes = 1024 <br />1 MB = 220 bytes = 1048576 byte<br />1 GB = 230 bytes = 1073741824<br />1 TB = 240 bytes =1099511627776 <br />
15. 15. CLOCK SPEED MEASUREMENT<br />“SPEED” means how fast it can process data<br />Every processor contains a system clock. The system clock control the speed of all operations within a computer.<br />The clock speed unit is measured in Hertz.<br />A Hertz is one cycle per second.<br />
16. 16. UNIT OF SPEED<br />