Topic 1: Introduction to Computers

1
Topic 1 Introduction to Computers

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

2
Computer components

• Central Processing Unit
• Memory
• Input/output devices
• Secondary storage

3
Computer Components
4
CPU
5
CPU

• Arithmetic/logic unit (ALU)
• Performs arithmetic operations (,-,...) and
  logical operations (lt, gt, ...)
• Control unit (CU)
• Decodes machine instructions and tells
• other components the required operations
• Registers
• store current instruction and values

6
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

7
CPU-Memory Interaction
Fetch-execute cycle
0 LDA 14
1 ADD 15
2 STA 14
3 HLT
.
14 10
15 7
Assume a is stored in 14 and b is stored in 15
Program
a a b
Result
14 17
15 7
8
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

9
Hard Disk Drive Basics

10
Connecting Computers

• Local Area Network (LAN)
• Wide Area Network (WAN)
• Internet
• World Wide Web (WWW)

11
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)

12
Computer Software

• Application Software ( Word, Excel, etc.)
• Computer Languages
• Low level languages (machine language)
• High level language (C, Java, Fortran, )

13
Running a High-level Language

• Generating a source file (editor) gt tst.c
• Translating to machine code (compiler)
  gttst.obj
• Linking the object file with other object files
  (linker) gttst.exe
• Copying the executable file into memory (loader)
• Integrated Development environment (IDE) combines
  all of these steps

14
Problem Solving with Computers (Software
Development Method)

• 1- Specify the problem requirement
• 2- 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 algorithmgt changing the
  algorithm to a programming language

15
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