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Topic 1: Introduction to Computers

Computer Hardware• Computer components• Connecting ComputersComputer Software • Operating System (OS)• Running a High-level LanguageProblem Solving with Computers • Software Development Method

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Computer components

•Central Processing Unit

•Memory

•Input/output devices

•Secondary storage

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Computer Components

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CPU

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CPU

• Arithmetic/logic unit (ALU) Performs arithmetic operations (+,-,...) and

logical operations (<, >, ...)• Control unit (CU) Decodes machine instructions and tells other components the required operations• Registers store current instruction and values

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Memory

• A collection of cells

• Each cell has an address and a value

• Random Access Memory (RAM)

Cells can be accessed randomly

• Ram is volatile

• All data stored in binary format

• Bit, byte and word are the unit of data

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CPU-Memory Interaction

0 LDA 14

1 ADD 15

2 STA 14

3 HLT

…. ……

14 10

15 7

14 17

15 7

Assume a is stored in 14and b is stored in 15

a= a + b

Result

Program

Fetch-execute cycle

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Input/output Devices

• Text-based and GUI-based interaction• Scanners, Touch screens• Monitor, printer, speakers

Secondary Storage •Floppy disk , CD (680 MB), DVD (4.717 GB), •Tape, Hard disk•File, Directory, Subdirectory, Folder

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Hard Disk Drive Basics

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Connecting Computers

• Local Area Network (LAN)

• Wide Area Network (WAN)

• Internet

• World Wide Web (WWW)

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Computer SoftwareOperating System (OS)

• Part of OS is stored on Read Only Memory (ROM)

• OS is responsible for directing all computer operations and resources

• Command line interface (Unix)

• Graphical user interface (Windows)

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Computer Software

• Application Software ( Word, Excel, etc.)

Computer Languages

• Low level languages (machine language)• High level language (C, Java, Fortran, …)

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Running a High-level Language

• Generating a source file (editor) => tst.c• Translating to machine code (compiler)

=>tst.obj• Linking the object file with other object files

(linker) =>tst.exe• Copying the executable file into memory

(loader)Integrated Development environment (IDE)

combines all of these steps

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Problem Solving with Computers (Software Development Method)

1- Specify the problem requirement2- Analyze the problem (input, output,

additional requirements). Modeling the problem (abstraction)

3- Design the algorithm to solve the problem (top-down design or divide and conquer)4- Implement the algorithm=> changing the

algorithm to a programming language

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Problem Solving with Computers (Software Development Method)

5- Test and verify the complete program, running the program several times with different data sets

6- Maintain and update the program, removing undetected errors

** Failure is part of the process **