1. Computer Organization, Eclipse Intro
CMSC 131 Object-Oriented Programming I
Computer Organization, Eclipse Intro
Dept of Computer Science
University of Maryland College Park
This material is based on material provided by Ben Bederson, Bonnie Dorr, Fawzi Emad, David Mount, Jan Plane

2. Software Overview Two levels  Operating System and Application
Operating system manages computer's resources; typically runs as soon as computer is turned on. Typical responsibilities:
Process management Determines when, how programs will run on
Memory management
I/O, window system
Security
Applications  programs users interact directly with; usually are explicitly run. Examples:
Word processors
Games
Music software
Java Programs
Etc
Enough about hardware. Let's talk about software!
SOFTWARE: 2 "levels" (operating system / applications)
1. operating system -- manages computer's resources.
typically runs as soon as computer is turned on.
* Process management -- determines which programs will run at what
time and how much CPU time each gets
* Memory management -- controls main memory and keeps programs from
interfering with one another
* I/O, window system, network control -- Programmers don't write this
stuff from scratch. Programs we write call on the operating system
to take care of the tricky details.
* Security enforcement -- user ID's passwords, file security, etc.
2. Applications software: (anything else!)
Word processors, games, spreadsheets, eclipse, everything

3. How Programs Are Executed
foo.exe
CPU
COPY
Program “foo” initially
stored in secondary
storage
Program copied into main memory
CPU executes
program instruction-by-instruction
Program execution:
programs are stored permanently in SECONDARY MEMORY.
the instructions are stored in "machine code" -- binary numbers
(Nobody writes programs in machine code -- we use other languages
which are typically translated into machine code by a "compiler".)
when you start up a program, it is copied (loaded) into PRIMARY MEMORY.
Now the CPU starts executing the instructions in the program.

4. Compilers Computers can only execute machine code
Compilers are programs for translating programs (“source code”) into assembler / machine code
compiler
source
asm/obj

5. Interpreters Another way to execute programs
Interpreters take source code as input
Interpreters execute source directly
Much slower than compiled programs
Debuggers are based on interpreters
Debuggers support step-by-step execution of source code
Internal behavior of program can be closely inspected
Common interpreter?
Javascript is most common current interpreter
Try these in browser bar:
Javascript:a=3
javascript:a=3;b=a+2
Javascript:alert(“Hello”)

6. Object-Oriented Terminology
Procedural-oriented languages
Programming centers around “actions” (verbs)
Object Oriented Languages
Centered around objects (nouns)
Objects
Principal entities that are manipulated by the program (nouns)
Class
A “blueprint”/recipe that defines the structure for one or more objects
Method
Java term for a “function”, a “procedure”, or a “subroutine”
This is the code that does something (verbs)
Why we prefer the object-oriented approach?
One big reason: recycling

7. Tools for Writing Programs
Good old days 
Text Editor  create source code files
Compiler  generate executables from source
Debugger  trace programs to find errors
Cycle between editing, compiling, running, debugging
Today, IDE (Integrated Development Environment)
Editor, compiler, debugger, version control rolled in one
IDE Examples
Eclipse  Free!! What we will use
Visual Studio
Netbeans
Others

8. Eclipse Fundamentals
Eclipse IDE allow us to create, edit, compile, run, debug, programs
Eclipse can be used for several languages; in this class Java
Eclipse installation
Eclipse tutorial

9. Eclipse Terminology Let’s run Eclipse
Workspace  folder/directory where your files are stored
You can switch workspaces
Projects
Project  collection of related files
Creating a program in Eclipse requires creating a project
Let’s create a project

10. Eclipse Terminology Perspective
Framework for viewing/manipulation programs
Three important perspectives
Java  creating, running programs
Debug  tracing, removing errors in programs
CVS repository  accessing/managing project files
Let’s change perspectives
Resetting perspective
Let’s create a program