Pointers in the 32-bit World in C programming language

In a 16-bit world (like MS-DOS) we could run only one application at a time. If we were to run another program we were required to terminate the first one before launching the second. As only one program (task) could run at a time this environment was called single-tasking environment. Since only one program could run at any given time entire resources of the machine like memory and hardware devices were accessible to this program. Under 32-bit environment like Windows several programs reside and work in memory at the same time. Hence it is known as a multi-tasking environment. But the moment there are multiple programs running in memory there is a possibility of conflict if two programs simultaneously access the machine resources. To prevent this, Windows does not permit any application direct access to any machine resource. To channelize the access without resulting into conflict between applications several new mechanisms were created in the Microprocessor & OS. This had a direct bearing on the way the application programs are created. This is not a Windows OS book. So we would restrict our discussion about the new mechanisms that have been introduced in Windows to topics that are related, to C programming. These topics are ‘Memory Management and Device Access’.