1. computer system overview1 The Effects of Computers Pervasive in all professions How have computers affected my life? How have computers affected my life? Internet Internet Computer Literacy Computer Literacy – knowing how to use the computer – knowing capabilities and limits

2. computer system overview2 History of Computers First Generation computers (1951-1958) First Generation computers (1951-1958) – vacuum tubes – used large amounts of electricity, heat – large and expensive – 1946 - ENIAC - computed trajectories for U.S. Army – 1951 - UNIVAC - first commercially available computer

3. computer system overview3 Second Generation computers (1959-1963) Second Generation computers (1959-1963) – Transistors,less heat,more reliable, less expensive Third Generation computers (1964-1970) Third Generation computers (1964-1970) – integrated circuits,less heat, higher speed Fourth Generation computers (1971-?) Fourth Generation computers (1971-?) – microprocessor Fifth Generation computers Fifth Generation computers – 1981 – Personal Computer, PC – Today - cheaper, smaller, better – reasoning?

4. computer system overview4 Computer Differences Microcomputers –pc –single user Minicomputer Systems –multiuser, typical - 20 terminals Mainframe Supercomputer

5. computer system overview5 Hardware I/O and Storage Devices Processor Unit –CPU - central processing unit brain – executes the instructions (program) stored in memory arithmetic logic unit (ALU) - operations and computations control section- executes instructions –primary storage section - main memory holds data and active program RAM - random access memory

6. computer system overview6 Machine cycle –Fetch control unit fetches instruction from memory –Decode translate instruction into signals –Execute ALU performs operation –Store

7. computer system overview7 Software System Software - software that controls overall operation of computer –Operating System - software that controls overall operation of computer Programming Environment Editor Compiler Interpreter Linker debugger Applications Software

8. computer system overview8 Programming Language –Machine language binary coded instructions operation code - typical machine 50-200 operand - data or address exa: 110011 - add instruction –Assembly language symbolic machine language low-level, machine dependent Requires assembler exa: ADD

9. computer system overview9 Assembly Language Exa: COMP$PAYPROC PUBLIC ; ;COMP$PAY - procedure to compute gross pay ;(PAY = HOURS * RATE) MOVAX,HOURS; multiplicand MULRATE+2; X second word of multiplier MOVPAY+2,AX; store the product in PAY ; MOVAX,HOURS; multiplicand MULRATE; times first word of multiplier ADDPAY+2,AX; add the product to PAY ADDPAY,DX; add the carry, if any RET; end procedure

10. computer system overview10 programming language cont'd high level –machine independent –standardized official description of the language exists –English-like –compiler - translates high-level language into machine code –interpreted - examined one line at a time –portable separate compiler is required for each language on each computer

11. computer system overview11 Languages BASIC FORTRAN COBOL PASCAL C,C++ ADA LISP java

12. computer system overview12 Computer Science Science of information representation and management –Technology of computers –The way information is structured and managed Systematic study of those algorithms which describe and transform information: the underpinning theory, analysis, planning, efficiency, realization, and application Computer is the tool

13. computer system overview13 Software engineering –Engineering –Project management –Personnel management –Programming language design Computer Architecture Artificial Intelligence

14. computer system overview14 technology Technology – externalizing human abilities into the things we make Paradigm – form or model evidencing a single theme or pattern –Paradigm shift Whole new ways of thinking emerge New bodies of knowledge emerge Chaos Shift in power Changes in the form of human expression

15. computer system overview15 The Computing Perspective Algorithmic conception of phenomena Simulation and experimentation Abstraction