Outline
204111
Computers and Programming
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อนันต ผลเพิ่ม
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Anan Phonphoem
anan@cpe.ku.ac.th
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Intro to computer
Computer components
How can we load and run program?
Programming languages
Problem solving and programming
Programming strategy
Intro to Pascal
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Program structure
Basic elements (reserved words, identifiers)
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Categories of Computers
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Personal Computer, Desktop computer
Notebook, Laptop, Palmtop
Use by one person at a time
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Workstation
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Minicomputer
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Categories of Computers
Microcomputer
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Faster speed
Many users at the same time
CAD Workstation
Unix Workstation
Server
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Client /Server (Networks)
Mainframe -> Supercomputer
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High computation power
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Computer Components
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Computer Components
Secondary
Memory
Main
Memory
HD
CPU
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Input Devices
Output Devices
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1
Computer Memory
1. Main Memory
1. Main Memory
2. Secondary Memory
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Store information
Memory
Address
000
001
002
003
...
100
-34.9
A
23
999
W
Memory Cell
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1. Main Memory
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2. Secondary Memory (Storage)
Memory Cell Æ Byte Æ Bit
1 Byte = 8 bits
Can be divided into 2 Categories
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RAM (Random Access Memory)
ROM (Read Only Memory)
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Floppy disk
Hard disk
CD-ROM
Tape
Information called “file” (data file, output file,
program file)
1 Kbyte = 210 = 1024 bytes
1 Mbyte = 220 = 1,048,576 bytes
1 Gbyte = 230 = 1,073,741,824 bytes
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Main VS. Secondary Memory
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Computer Components
Secondary
Memory
Main Memory
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Much faster
More expensive
Volatile (RAM)
Main
Memory
Secondary Memory
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HD
Slower
Less expensive
Permanent
CPU
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Input Devices
Output Devices
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Central Processor Unit (CPU)
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How can we load and run program?
Retrieve information from memory
Calculate
Put back results to memory
Intel / AMD (Pentium / Athlon)
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Boot process
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Load OS into Memory
Tell user to load and run Program “p1”
User start using program
Secondary
Storage
HW
OS p1
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How can a non-machine
language program be executed?
Programming Language
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Machine Language
Assembly Language
High-Level Language
CPU can execute only the machine
language
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2 methods
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Interpretation
Translation
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The interpretation Process
Translation Process
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Source Program
Interpreter
(on computer)
USER
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Output
Input Data
Translation Phase
Link Phase
Execute Phase
Source
Program
Translator
Output
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Library
Object
Program
CPU
Linker
Execute
Program
Input Data
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Translators
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High-Level Languages
Assembler (assembly)
Compiler (High-level language)
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Procedural Language
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Fortran
Cobol
Basic
C
Pascal
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Object-Oriented Language
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Functional Language
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„ Lisp
Logic Language
„ Prolog
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C++
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Problem Solving and
Programming
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Programming Strategy
Solve Problems
Combine art and science
Art
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Transform a description (word to equation)
Difficult (problem is not clear, input, output)
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Science
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Knowledge of problems
Equation and formula
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Introduction to Pascal
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Don’t rush to key in the computer
Think carefully about the problem
Try to solve by hand
Plan your program
Test by hand if possible
Start programming
Program Compilation
Testing / Debug
Documentation
Maintenance
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Pascal Program Structure
Procedural programming language
Developed by Prof.Niklaus Wirth
(Switzerland, 1970s)
Named in honor to mathematician,
Blaise Pascal
Most popular -> Turbo Pascal
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Program Heading
Declarations
Main Routine (Program body)
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Pascal Program Structure
Basic Elements of Pascal
Program Heading
program myFirstProgram;
const
Declarations
myStudentId = 1234567;
var
courseTaken: integer;
begin
Program Body
write(‘Please Enter a number of courses’);
read(‘courseTaken’);
writeln(‘Student’, myStudentId, ‘ takes ’, courseTaken, ‘
courses in this semester’);
end.
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Character set
Reserved words
Identifiers
Constants / Variables
Statement / Expression
Function / Procedure
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Reserved Words (คําสงวน)
Character Set
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Three categories
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Letter (A…Z, a…z)
Digit (0…9)
Special character (+ - * / _ = ! <> []{})
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Predefined meaning and usage
Cannot be redefined by the
programmer
Examples
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program
begin / end
const / var
etc.
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Reserved Words (คําสงวน)
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Identifiers (คําบงชี้)
program myFirstProgram;
const
myStudentId = 1234567;
var
courseTaken: integer;
begin
write(‘Please Enter a number of courses’);
read(‘courseTaken’);
writeln(‘Student’, myStudentId, ‘ takes ’, courseTaken, ‘
courses in this semester’);
end.
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Symbolic names for program elements
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Rules for constructing identifiers
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Program name
Variable name
Data Type name
Etc.
Letters, digits, and under score (_)
First characterÆ letter
Can be long (63 char)
Reserved words are not allowed
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Identifiers (คําบงชี้)
Identifier examples
program myFirstProgram;
const
myStudentId = 1234567;
var
courseTaken: integer;
begin
write(‘Please Enter a number of courses’);
read(‘courseTaken’);
writeln(‘Student’, myStudentId, ‘ takes ’, courseTaken, ‘
courses in this semester’);
end.
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Valid examples
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score, count, total
score1, count99, total09
score_1, count_99, total_99
myStudentId
my_student_id
Invalid examples
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point&score
total-number
9points
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Notes for Identifiers
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Standard Identifiers
Identifiers are case-insensitive
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program myFirstProgram;
const
myStudentId = 1234567;
var
courseTaken: integer;
begin
write(‘Please Enter a number of courses’);
read(‘courseTaken’);
writeln(‘Student’, myStudentId, ‘ takes ’, courseTaken, ‘
courses in this semester’);
end.
mystudentId
Mystudentid
MYSTUDENTID
Some identifiers are predefined
meanings (Standard Identifiers)
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interger, real
write, writeln, read, readln
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