Q. Why we use Debugger?

Debugger is a program which allows the user to test as well as debug the object file.  Theuser can use this program to perform subsequent functions. 

• Make alterations in the object code.
• Inspect and modify the contents of memory.
• Set breakpoints and execute a segment of the program and display register contentsafter execution.
• Trace execution of specified segment of program and display memory and register contents after the execution of every instruction.
• Disassemble a segment of the program it implies to convert the object code in source code or mnemonics.

In brief to run an assembly program you might need your computer: 

• A word processor such as notepad
• TASM, MASM or Emulator
• LINK.EXE it can be involved in assembler
• DEBUG.COM for debugging if need to be.