Digital Data Representation

1. Digital Data Representation Class Handout

2. Data Representation Basics Representing Numbers, Text, and Pictures Quantifying Bits and Bytes Circuits and Chips Digital Data Representation

3. Data representation refers to the form in which data is stored, processed, and transmitted. Digital devices work with distinct and separate data. Analog devices work with continuous data. Digitizing is the process of converting analog data into a digital format. Data Representation Digital=DistinctOn / Off Analog=Continuous

4. Numeric data Composed of numbers that might be used in arithmetic operations. Decimal number system has 10 symbols. Binary number system has only two symbols (0, 1). Character data Composed of letters, symbols, and numerals that are not used in arithmetic operations. ASCII, Extended ASCII, EBCDIC, and Unicode. Picture Data Composed of a series of dots. Each dot is assigned a binary number for color. Sound Data Is characterized by the properties of a sound wave. The wave can be represented digitally by sampling it a various points and converting those points into digital numbers. Representing Numbers, Characters (Text), Pictures, and Sound

5. Memory Capacity • Bit: • Short for binary digit (0s and 1s), the only data that a CPU can process. • Byte: • An 8-bit string of data, needed to represent any one alphanumeric character or simple mathematical operation. In this picture, one byte, 01001000, represents the letter H

6. Numeric and Character Data Representation

7. Hierarchy of Memory Capacity-Quantifying Bits and Bytes • Bit • One binary digit • Byte • 8 bits • Kilobyte (KB) • Approximately one thousand bytes, (1024 or 210 bytes) • Megabyte (MB) • Approximately one million bytes (1,048,576 bytes, or 1,024 x 1,024 or 220 bytes). • Gigabyte (GB) • Actually 1,073,741,824 bytes (1,024 x 1,024 x 1,024 or 230 bytes). • Terabyte • One trillion bytes, or 240 bytes. • Petabyte • One thousand terabytes, or 250 bytes. • Exabyte • One thousand petabytes, or 260 bytes. • Zettabyte • One thousand exabytes.

8. An integrated circuit (computer chip) is a super-thin slice of semiconducting material packed with microscopic circuit elements. DIP=Dual In-line Package PGA=Pin Grid Array Circuits and Chips

9. How do bits and bytes fit together with chips and circuits? • Bits take the form of electrical pulses that can travel over circuits. • The 1 bit might represent an elevated voltage, such as 5 volts, whereas a 0 bit is represented by a low voltage, such as 0. • The system board is a circuit board to which a multitude of electronic components are mounted. • Motherboard

10. Programs and Instruction Sets Processor Logic Digital Processing

11. Computers, portable media players, handheld computers, and smart phones all work with digital data. Computer programmers create programs that control digital devices. These programs are usually written in a high-level programming language. The human-readable version of a program created in a high-level language is called the source code. Programs and Instruction Sets

12. The procedure for translating source code into 0’s and 1’s can be accomplished by a compiler or an interpreter. Programs and Instruction Sets

13. A collection of preprogrammed activities a microprocessor is hardwired to perform is called an instruction set. Additions, subtractions, counting, comparisons, etc Each instruction has a corresponding sequence of 0s and 1s. 00000100 might = Add. The list of codes for a microprocessor’s instruction set, called machine language, can be directly executed by the processor’s circuitry. This end product, the 1s and 0s, is called machine code. Programs and Instruction Sets

14. A machine code instruction has two parts. The op code and the operand. An op code (short for operation code) is a command word for an operation such as add, compare, or jump. The operand for an instruction specifies the data (or the address of the data) for the operation. Programs and Instruction Sets Op Code Operand 00000100 00000001 00100100 00011001 01010100 00100001

15. Many machine language instructions might be needed to equal a simple high-level program that counts to 100. Programs and Instruction Sets

16. The arithmetic logic unit (ALU) is the part of the microprocessor that performs arithmetic operations. The ALU uses registers to hold data that is being processed. The microprocessor’s control unit fetches each instruction, just as you get each ingredient out of a cupboard or the refrigerator. The term instruction cycle refers to the process in which a computer executes a single instruction. Processor Logic-What happens inside a computer chip

17. Processor Logic-What happens inside a computer chip

18. Processor Logic-What role does the Control Unit play