Data Representation in Computers
- 2. Units 8 bits = 1 byte 1024 bytes = 1 kilobyte 1024 kilobytes = 1 megabyte 1024 megabytes = 1 gigabyte 1024 gigabytes = 1 terabyte Four bits, half a byte, is called a nibble
- 3. Denary to Binary conversion
- 4. Denary to Binary conversion 11100 1 Start from the bottom and get the reminders 00000011 is binary for 3 but so is 11. You do not need the leading zeros for it to be a valid number but we tend to write groups of 8 bits because computers usually store data in bytes.
- 5. Addition and Subtraction in binary 10010+101 10101100 + 00010001 00101101+ 10000101 00101101+ 10000111 What is the biggest decimal number you can store using: • 4 bits? • 2 bytes?
- 6. Addition and Subtraction in binary 11111100 + 00001111 If you cannot represent the number in that amount of space because it is too big, then we get overflow. 8 bits is 255
- 7. Addition and Subtraction in binary 11111100 + 00001111 If you cannot represent the number in that amount of space because it is too big, then we get overflow. 8 bits is 255
- 8. Hexadecimal (hex) 8 bits is 255
- 9. Hexadecimal (hex) 8 bits is 255 1011100 Separate them by 4 units: 0101 1100 5 12 5C in hex
- 10. Hexadecimal (hex) 8 bits is 255 182 182/16=11 remainder 6 11=B in hexa 182 in denary=B6 in hex
- 11. Characters PCs mainly uses ASCII, American Standard Code for Information Interchange ASCII uses 7bits From 0000000 to 1111111 Can represent up to 128 characters Unicode: or 32 bits per character so can code or 4,294,967,296 EBCDIC(pronounced eb-sid-ic): Extended Binary Coded Decimal Interchange Code, 8-bit encoding. 256 different characters in its character set.
- 12. Images Computer to interpret an image and rebuild the picture it must know some other things about the data file. Picture’s resolution is 8x11 pixels and the colour depth is 2 bits per pixel. Data about the data file itself is called metadata. The number of bits per pixel is referred to as the colour depth.
- 13. Images To store an image on a computer the image is broken down into very small elements called .
- 14. Sound Sound waves are analogue, which means continuously changing. In order to store sound waves in the computer these signals have to be converted in to numerical values(binaries). This is achieve with Analogue-to-Digital Converter (ADC). For sound waves, the analogue signal is converted as follows: • Measure the amplitude (height of wave) at regular intervals (sampling) • Store the values as a series of binary numbers in a file
- 15. Quality of Sound Sample Resolution The number of bits used to store each sample. The more bits that are used, the better the accuracy of the sound file. Sample Interval The time period between taking samples/measurements. The more frequently the sound is sampled, the better the quality of playback. Synthesis: Sound synthesis is when the sound is recreated from this file by the computer, and played through speakers.
- 16. Instructions Each type of processor has its own type of machine code – a specific set of instructions that it can execute. This is called an instruction set. The group of bits that represents the operation is called the opcode If the programming language allowed us to specify how many steps to move RIGHT 90 (Turn 90° to the right) MOVE 2
- 17. Instructions If the programming language allowed us to specify how many steps to move RIGHT 90 (Turn 90° to the right) MOVE 2 In the program, number steps to move can be stored in a variable. Move numSteps An opcode, which is the binary number representing the operation to be carried out. e.g. RIGHT, MOVE The operand (data) that the operation will use. The data can be an actual value (e.g. 5) or an address in memory where the data can be found (a variable).
Editor's Notes
- #3: Beginning course details and/or books/materials needed for a class/project.
- #4: A schedule design for optional periods of time/objectives.
- #5: A schedule design for optional periods of time/objectives.
- #6: Introductory notes.
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