Assembler
The Assembler is used to translate the program written in Assembly language into machine code. The source program is a input of assembler that contains assembly language instructions. The output generated by assembler is the object code or machine code understandable by the computer.
Compiler
The language processor that reads the complete source program written in high level language as a whole in one go and translates it into an equivalent program in machine language is called as a Compiler.
Example: C, C++, C#, Java
In a compiler, the source code is translated to object code successfully if it is free of errors. The compiler specifies the errors at the end of compilation with line numbers when there are any errors in the source code. The errors must be removed before the compiler can successfully recompile the source code again.>
Linker
A linker is special program that combines the object files, generated by compiler/assembler, and other pieces of codes to originate an executable file have. exe extension. In the object file, linker searches and append all libraries needed for execution of file. It regulates memory space that code from each module will hold. It also merges two or more separate object programs and establishes link among them. Generally, linkers are of two types :
1. Linkage Editor
2. Dynamic Linker
Loader
The loader is special program that takes input of object code from linker, loads it to main memory, and prepares this code for execution by computer. Loader allocates memory space to program. Even it settles down symbolic reference between objects. It in charge of loading programs and libraries in operating system. The embedded computer systems don’t have loaders. In them, code is executed through ROM. Generally, loader has three types of approach :
1. Absolute loading
2. Relocatable loading
3. Dynamic run-time loading
