Dynamic Loading

The size of physical memory is limited. In order for the memory utility goes well, then we using dynamic loading. In this way, routine-routine will only be called if required.

Following illustration, all routines are stored on disk in a format that can be reallocated (relocatable load format). The main program is placed in memory and executed. When a routine routine calls another, the first thing done is to check whether there are other routines already loaded. If not, relocatable linking loader is called to put the routines that and memory needed to renew the program address table. Then, control is given to the routine new call.

The advantage of dynamic loading is not used routine never gets called. This method is useful in code that amounted to much, when it emerged the wrong case as routine. Although a large code size, the portion that is used can be much smaller. The operating system does not create a dynamic loading mechanism, but only provide routine routine to implement this mechanism. Users who design its own program in order program uses dynamic loading system.