14 June 2010

Understanding Processor Architecture: Machine and Assembly Language

The processor understands only the machine language, whose instructions consist of strings of 1s and 0s. Machine language is closely related to the assembly language. We prefer to use the assembly language rather than the machine language. Programming in the assembly language also requires knowledge about the processor architecture.

Assembly language programming is referred to low-level programming because each assembly language instruction performs a much lower-level task compared to an instruction in a high-level language. Assembly language instructions are processor specification dependents. For example, a program written in the Intel assembly language cannot be executed on the PowerPC processor.

Here are some IA-32 assembly language examples:
inc result
mov class_size, 45
and mask1, 128
add marks, 10

The first instruction increments the variable result. This assembly language instruction is equivalent to


in C. The second instruction initializes class_size to 45. The equivalent statement in C is

class_size = 45;

The third instruction performs the bitwise and operation on mask1 and can be expressed in C as

mask1 = mask1 & 128;

The last instruction updates marks by adding 10. In C, this is equivalent to

marks = marks + 10;

We can translate the assembly language instructions to the equivalent machine language instructions. Machine language instructions are written in the hexadecimal number system. Here are some IA-32 machine language examples:



Machine language (in hex)


No operation90

inc result


mov class_size, 45


and mask, 128

Logical and80260E0080

add marks, 10

Integer addition83060F000A


  • Guide to RISC Processors for Programmers and Engineers by Sivarama P. Dandamudi, Springer (2005), ISBN 0-387-21017-2.


Anonymous said...

Thanx this is very useful tip actually assembly language is kind of a language very difficult.

7chip said...

i have a blog ,subject is 89c51.i want some more information about 89c51 project.do you have.if yes just visit my blog and comment it anywhere in the blog

Inhimak said...

8051 micro controller is best approach for learning that what is micro controller and its architect.

What is 8051?