 Why?  Because it can be programmed to do more than one specific task. ◦ Accountants ~ tax forms etc. ◦ Machinists ~ control drilling, lathes etc. ◦ Medical uses ◦ Simulation in real time ~ space

 Computers are Designed to do what the instruction set(software) says to do.  Usage demands patience and persistence.  User must learn the language (commands).  User must know syntax for a particular language.

 Hardware: implies physical components.  Software : implies: a. Operating system software. b. Application software.

CPU Main Memory Output device Input device Secondary Storage

 Input Output  Instruction Result ALU Control Unit

 ALU: arithmetic and Logic Unit.  (does the math)  Control Unit: 1.fetches- from main memory, the next instruction in a sequence of instructions. 2.Decode-Instruction is coded in the form of a number. The control unit decodes the instruction and generates an electronic signal. 3.Executes: signal is routed to a device.

 RAM---random access memory: a device that holds information. (Usually a temporary holding because when the computer is turned off the RAM is erased.)

 Hard disk: holds information for a long time.  Other devices:  Flash drive  Optical drive (compact disk or DVD)

 Output devices: Monitor Printer Disk drives  Input devices:  Keyboard  Mouse  Disk drives

 Operating System---set of programs that manage the computer hardware devices and control their processes.  Single task—one program at a time.  like MS-DOS  Multi-tasking---runs multiple programs all at once. It divides the CPU memory among executable programs. Like Unix, XP, Windows 7.

 Falls into categories based upon the number of users.  Multi-user---Unix, Linux  Single User DOS, Windows

 If a Program is a set of instructions a computer follows; then a programming language is a special code(language) used to write the program.  Low level: implies machine language  High-level: human readable

 Basic  Fortran  COBOL  Pascal  C  C++  C#  Java  Forth/Fifth  Visual Basic

 Source Code---source file, text editors  Object code---checks for syntax  Executable code---Object code +library routines