Assembler Compiler Interpreter

ASSEMBLER

To convert the assembly language into machine code. Translate mnemonic operation codes to their machine language equivalents. Assigning machine addresses to symbolic labels.

The assembler can also process assembler directives. Assembler directives (or pseudo- instructions) provide instructions to the assembler itself. They are not translated into machine instructions E.g. START (specify name and starting address for the program). END (indicate the end of the source program and (optionally) specify the first executable instruction in the program)

Programmer write a program using a sequence of assemble instructions. This sequence of assembler instructions, known as the source code/source program, then specified to the assembler program when that program is started. It translates a source code into machine language. The output of the assembler program is called the object code or object program.

We use Flat Assembler (FASM) o Download on: o o Download for Windows The Linker is the program that ties all the loose end together and makes a single program out of the pieces. FASM comes with its own built in linker

Go to “Start -> Control Panels -> System - > Advanced -> Environment Variables Make a new system variable, called include, with value C:\(your directory of fasm folder) Run fasmw.exe Note: Please refer to the

Inside FASM, open the EXAMPLES directory, open the directory called HELLO, open the file Hello.asm Go to Run menu, Compile and Run The program will assemble and then the pop message box up on the screen

include 'win32ax.inc' ; you can simply switch between win32ax, win32wx, win64ax and win64wx here.code start: invoke MessageBox,HWND_DESKTOP,"Hi! I'm the example program!",invoke GetCommandLine,MB_OK invoke ExitProcess,0.end start

First line, win32ax.in is a special macro file. The next line,.code tells the assembler we are going to include some code now. The line start: is a label. It gives a name to one of the lines. The program is ended with the.end directive. The execution of the program will begin at this point The remaining two line are calls to the Windows API to tell it to display a message box and then quit.

COMPILER

A program that changes source code (high- level language) to object code which that can be executed by a machine. Compiler: o Checks syntax of program o Checks at a time all the program Primary reason for compiling source code is to create an executable program Examples of compiler based language: C, C++, JAVA

Executables: Files that actually do something by carrying out a set of instructions. E.g.,.exe files in Windows Once the executable is there, it can be called by the user to process the given inputs to a program and produce the desired outputs.

Some of examples of Compiler: o Microsoft Visual Studio o BlueJ o Quincy 2005 We use Quincy 2005 (Open Source) Link: We use C++ programming language.

Open Quincy File -> New -> C++ Source File -> OK File -> Save as.. -> Hello.cpp Write the following code: #include using namespace std; int main() { cout << "Hello World!" << endl; return 0; }

The first line #include, input/output library The second line using namespace std;, allows us to group a set of global classes, objects and/or functions under a name int main() { }, the main function of program cout << "Hello World!" << endl; print the “Hello World!” message to the screen. return 0;, terminate the main function of program. A return value of 0 means that the program finished correctly

INTERPRETER

A computer program that executes instructions written in a programming language and do not produces the executable file. Interpreter: o Checks the keywords of a program o Taking one instruction at a time and convert it into machine language before taking upon the next instruction. Examples of interpreter based language: o PHP, JavaScript, BASIC

We use JavaScript language. JavaScript engine is specialized computer software which interprets and executes JavaScript. Mostly used in web browsers.

Open Notepad -> Save as.. -> Name the file as hello.html Write the following code: name = prompt("Hello World")

, open a html page, put all the website contents inside <script), open a script function name = prompt("Hello World"), shows the Hello World! Message, close the script function, close the body of a web page, close a html page

Assembler = To convert the assembly language into machine code. Compiler = A program that changes source code (high-level language) to object code which that can be executed by a machine. A computer program that executes instructions written in a programming language and do not produces the executable file.