Computer Electronic device Accepts data - input Processes it according to a given set of instructions Produces results - output input output Computer

Input, Output, Computer Program Input – unprocessed data manipulated by the computer Output – processed information or results produced by the computer The set of instructions that the computer follows is called a computer program

Computer System hardware the physical equipment used to process a data software computer programs

Hardware CPU 010 111 ..... Main Memory Secondary I/O Devices

Hardware Main Memory Input Devices Output Devices CPU

Input/Output Devices Input devices keyboard, mouse enter data and programs into the computer Output devices printer, monitor display the results processed by the computer

Memory Bit - Binary Digit Byte = 8 bits Main Memory Nonpermanent Rapid Access Low Capacity Secondary Storage Permanent Non Rapid High Capacity Bit - Binary Digit Byte = 8 bits KB = KiloBytes = 1024 bytes =210 MB = MegaBytes = 1,048,576 bytes = 220 GB = GigaBytes = 230 bytes

CPU – Central Processing Unit Control Unit Directs the processing operations Coordinates the flow of data to Main Memory and ALU Arithmetic Logic Unit (ALU) performs Arithmetic operations Logic operations

Software Operation Systems Application Software DOS UNIX Windows Word Power Point Emacs

The First Program /*Author: Yana Date: 10/09/2004 Prints the text ‘Hello World!’ */ #include <stdio.h> int main(){ printf( “Hello World!\n” ); return 0; }

Compilation Process High Level Language Compiler Machine Language

Compilation Process Executable File 010111001011101110….. Source File Compiler int main(){ printf(….); } Object File Object File/Library 1001001 1010101001 1010100…. 010010001 0101001 010100…. Linker Executable File 010111001011101110…..