DOS means Disk Operating System.
DOS is universally compatible with all PCs and allows direct access to hardware.
I’ve noticed why most of financial company used DOS based system rather than more advanced programming languages and what advantages does it have than the other programming languages?
Advantages are that DOS will run on a much smaller system, gives you more "direct" control of the processes, Because of smaller size will "boot" much faster than ANY windows version, Is easier to write "special purpose" programs for, so long as they don't require "fancy" graphics and Allows you to make use of the "old, slow" system
You got the right point. DOS  (Disk operating system) is the most popular microcomputer operating system, it has been made for IBM computer and it has the compatibility to sold world wide ever. DOS can able to go on with more than thousand of application and probably the most point of it’s popularity is it’s easy ness of use. It is very easy for novices also. And many publications and books are available for DOS.
It runs on cheaper IBM PC and a very important point is that, theirs no need a highly configured and featured computer for running DOS. Probably for this advantages, DOS is gaining preferences than any other advanced programming language. Â http://home.olemiss.edu/info/notactive/
