Assembly Language Programming for X86 Processors: Optimizing Subroutines in Assembly Language

What is Assembly Language?
Each personal computer has a microprocessor that manages the computer’s arithmetical, logical, and control activities.

Each family of processors has its own set of instructions for handling various operations such as getting input from keyboard, displaying information on screen and performing various other jobs. These set of instructions are called ‘machine language instructions’.

A processor understands only machine language instructions, which are strings of 1’s and 0’s. However, machine language is too obscure and complex for using in software development. So, the low-level assembly language is designed for a specific family of processors that represents various instructions in symbolic code and a more understandable form.

Advantages of Assembly Language
Having an understanding of assembly language makes one aware of −

How programs interface with OS, processor, and BIOS;
How data is represented in memory and other external devices;
How the processor accesses and executes instruction;
How instructions access and process data;
How a program accesses external devices.
Other advantages of using assembly language are −

It requires less memory and execution time;

It allows hardware-specific complex jobs in an easier way;

It is suitable for time-critical jobs;

It is most suitable for writing interrupt service routines and other memory resident programs.