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Steps of creating Assembly language program in 8051

On this website, we have already discussed about the Embedded C programs on 8051 and why we should use C language instead of assembly language. But, many concept can be cleared through assembly language. In assembly language, one has to learn instruction sets and use them to write the program using Assembler Derivatives or Editors.

Steps to write Assembly Language program:

1. First of all, install Assembler editors which you find compatible for your microcontroller and computer. There are many assemblers are available on Internet for free from Keil and Macro which can be used to write and assembly language program.
  • Notice that the editor must be able to produce an ASCII file.
  • For many assemblers, the file names follow the usual DOS conventions, but the source file has the extension “asm“ or “src”, depending on which assembly you are using.
2. After writing a program in assembler editor, save your file using extension ".asm". The “asm” source file containing the program code created, is fed to an 8051 assembler. Important features of "asm" extension saved file:-
  • The assembler converts the instructions into machine code.
  • The assembler will produce an object file and a list file.
  • The extension for the object file is “obj” while the extension for the list file is “lst”.
3. Now, Assembler require the step- linking. It can be considered similar to debugging in the Keil micro-vision software while writing an embedded C program. The linker program takes one or more object code files and produce an absolute object file with the extension “abs”. This abs file is used by 8051 trainers that have a monitor program.

4. Next the “abs” file is fed into a program called “OH” (object to hex converter) which creates a file with extension “hex” that is ready to burn into ROM.
The latest Windows-based assemblers combine step 2 through 4 into one step which makes the individual steps less cumbersome and saves time. Assemblers like Asem-51 can be used to program assembly language.

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