1. Basic Concepts: computer, program, programming …
COM S 207
Basic Concepts: computer, program, programming …
Instructor: Ying Cai
Department of Computer Science
Iowa State University

2. In the beginning Everything in computer is coded as 0 and 1
lowercase "a" 
integer 20  10100

3. Bit: 1 digit (either 0 or 1) Byte: 8 bits Kilo (K): 1024 Mega (M): 1024 * 1K Giga (G): 1024 * 1M

4. What is computer about
8-bit, 16-bit, 32-bit, 64-bit CPU?

5. Computer Anatomy

6. Program A sequence of instructions for a computer to execute
All instructions are encoded into a string of 0/1
Program = stored instruction
Program = CODE + data

7. Programming
The act of writing programs

8. Programming language Machine language
Computers use the alphabet 0 and 1 ONLY.
Instructions are built from combinations of 0 and 1!
Example
might mean ADD 1 and 2

9. Programming language Assembly language
Still machine language alike, but more readable
Example: ADD 1 and 2 

10. Programming language High-level language: English-like languages
FORTRAN, COBOL, Pascal, Basic, C, Icon
C++, Java, ML
Scheme, Lisp,
Prolog
Perl, Python, Ruby

11. Language Elements Data types Decision (if, switch, etc.)
Primitive (integer, character, double, boolean, etc.)
Constructed (string, list, array, object, etc.)
Decision (if, switch, etc.)
Loop (for, while, until, etc.)
To write a program, it is critical that you understand the syntax and semantics of each instruction (also called statement).

12. Compiler
Convert a program into machine language instructions that can be executed by a computer
Compiler

13. Platform dependency
In general, different languages and platforms need different compilers
Portability and convenience are issues
Compiler for Unix
Compiler for Linux
:::
Compiler for Mac

14. Java Virtual Machine
A virtual machine that can execute Java binary code

15. Java Compiler
Convert a program into machine language instructions that can be executed by a computer

17. Tools Editor: allows you to enter and edit instructions Compiler
Programmer converts pseudo-code (which he understands) to java code (something java compiler can understand)
Compiler
Converts java code (something java compiler can understand) to class files (something that a Java Virtual Machine can understand)
JVM (Java Virtual Machine): executes/runs class files
Debugger
Allows you to have the JVM execute one instruction at a time and lets you see what is going on during the execution.
This will help you to find runtime errors.

18. Tools Integrated Development Environment (IDE): (e.g., Eclipse)
has all above tools integrated into one tool.