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computer system overview 1
The Effects of Computers
• Pervasive in all professions
• How have computers affected my How have computers affected my life?life?
• InternetInternet• Computer LiteracyComputer Literacy
– knowing how to use the computerknowing how to use the computer– knowing capabilities and limitsknowing capabilities and limits
computer system overview 2
History of ComputersHistory of Computers
• First Generation computers (1951-First Generation computers (1951-1958)1958)– vacuum tubesvacuum tubes– used large amounts of electricity, heatused large amounts of electricity, heat– large and expensivelarge and expensive– 1946 - ENIAC - computed trajectories for 1946 - ENIAC - computed trajectories for
U.S. ArmyU.S. Army– 1951 - UNIVAC - first commercially 1951 - UNIVAC - first commercially
available computeravailable computer
computer system overview 3
• Second Generation computers (1959-1963)Second Generation computers (1959-1963)– Transistors,less heat,more reliable, less Transistors,less heat,more reliable, less
expensiveexpensive
• Third Generation computers (1964-1970)Third Generation computers (1964-1970)– integrated circuits,less heat, higher speed integrated circuits,less heat, higher speed
• Fourth Generation computers (1971-?)Fourth Generation computers (1971-?)– microprocessor microprocessor
• Fifth Generation computersFifth Generation computers– 1981 – Personal Computer, PC1981 – Personal Computer, PC– Today - cheaper, smaller, better Today - cheaper, smaller, better – reasoning?reasoning?
computer system overview 4
Computer Differences
• Microcomputers – pc– single user
• Minicomputer Systems– multiuser, typical - 20 terminals
• Mainframe
• Supercomputer
computer system overview 5
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
computer system overview 6
Machine cycle
– Fetch • control unit fetches instruction from memory
– Decode • translate instruction into signals
– Execute• ALU performs operation
– Store
computer system overview 7
Software
• System Software– Operating System - software that controls - software that controls
overall operation of computeroverall operation of computer
• Programming Environment• Editor• Compiler• Interpreter• Linker• debugger
• Applications Software
computer system overview 8
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
computer system overview 9
Assembly Language Exa:COMP$PAY PROC PUBLIC
;
; COMP$PAY - procedure to compute gross pay
; (PAY = HOURS * RATE)
MOV AX,HOURS ; multiplicand
MUL RATE+2 ; X second word of multiplier
MOV PAY+2,AX ; store the product in PAY
;
MOV AX,HOURS ; multiplicand
MUL RATE ; times first word of multiplier
ADD PAY+2,AX ; add the product to PAY
ADD PAY,DX ; add the carry, if any
RET ; end procedure
computer system overview 10
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
computer system overview 11
Languages
• BASIC • FORTRAN • COBOL• PASCAL• C,C++• ADA• LISP• java
computer system overview 12
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
computer system overview 13
• Software engineering– Engineering– Project management– Personnel management– Programming language design
• Computer Architecture
• Artificial Intelligence
computer system overview 14
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
computer system overview 15
The Computing Perspective
• Algorithmic conception of phenomena
• Simulation and experimentation
• Abstraction