Source:- Freshersworld
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 like getting input from keyboard, displaying information on screen and performing various other jobs. These set of instructions are called 'machine language instruction'.
Processor understands only machine language instructions which are strings of 1s and 0s. 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
An understanding of assembly language provides knowledge of:
Interface of programs with OS, processor and BIOS;
Representation of data in memory and other external devices;
How processor accesses and executes instruction;
How instructions accesses and process data;
How a program access external devices.
Current usage
There have always been debates over the usefulness and performance of assembly language relative to high-level languages. Assembly language has specific niche uses where it is important; see below. But in general, modern optimizing compilers are claimed to render high-level languages into code that can run as fast as hand-written assembly, despite the counter-examples that can be found. The complexity of modern processors and memory sub-systems makes effective optimization increasingly difficult for compilers, as well as assembly programmers. Moreover, and to the dismay of efficiency lovers, increasing processor performance has meant that most CPUs sit idle most of the time,[citation needed] with delays caused by predictable bottlenecks such as I/O operations and paging. This has made raw code execution speed a non-issue for many programmers.
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