1. Software Development Environment
ICS 3U0

2. Today’s Agenda Program Execution Evolution of Programming Languages
Integrated Development Environment (IDE)

3. The Basics What is an operating system?
An OS is software that manages computer hardware resources and provides common services for computer programs. For example: Windows 8, MacOS or UNIX
What is a computer program?
A computer program provides a set of instructions telling the computer what to do. On a grander scale, also known as a software application. For example: Google Chrome, Minecraft, mylittleprogram.py
What is a programming language?
Formal language that a programmer uses to develop computer programs.
For example: C++, Turing, Java, Visual Basic, and Python

4. Program Execution When a computer program is executed:
The program is stored in memory (RAM).
CPU fetches instructions and data from there via the system bus.
CPU decodes, and executes the stored instructions of the program sequentially, inputting data as needed, and outputting results via the bus.
Steps 2-3 repeated until the program has completed.

5. Another Look at the CPU Arithmetic-Logic Unit (ALU)
Performs arithmetic operations (add, sub, mult, div).
Performs logical operations (<, >, =).
Allows computers to calculate and compare.
Control Unit
Directs the movement of electronic signals between memory and the ALU.
Coordinates control signals between CPU and input/output devices.
Tells the computer system how to execute a program.

6. Evolution of Programming Languages
Machine Code
Machine code or machine language is a set of instructions executed directly by the CPU. Each instruction performs a very specific task, such as an ALU operation on a unit of data in memory. Every program directly executed by a CPU is made up of a series of 0’s and 1’s.
Assembly Code
Assembly code is a step up from machine code. Although more easily understood by humans, it cannot be directly understood by the CPU. A program called the assembler translates assembly language programs into binary machine code that can be decoded by the CPU.

7. Evolution of Programming Languages … continued
Source Code
Source code consist of instructions or statements that look similar to English using common mathematical notation. It is really the only type of code that is readable by people. It is the code that is associated with high-level languages such as C++, Java or Python.
The instructions written using high-level languages must be converted into machine code so that can be understood by the CPU.
Complier/Interpreter
A compiler or interpreter translates source code written using high-level language (i.e., code that people can actually read) to machine code (i.e. 1’s and 0’s)

8. Compiler Vs. Interpreter
When a program is created, it may be run in one of two ways:
Compiled: a program is converted into a machine-readable format using a binary encoding.
Interpreted: The program requires a separate program, called an interpreter, to translate program instructions on-the-fly.
Some programming languages, like C/C++, are compiled.
Others, like Java or Python, are interpreted.

9. Compiler Vs. Interpreter

10. Integrated Software Development Environment - IDE
An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development.
An IDE normally consists of a 
Source code editor
Debugger
Compiler or interpreter

11. Common IDE’s
Java – Eclipse, Ready to Program, Dr. Java are common IDE’s used to develop programs in Java.
Ruby – Textmate is a common IDE used to develop programs in Ruby
Python – Pycharm, Eclipse and IDLE are common IDE’s used to develop programs in Python.