Memory Management

Basic Concepts
To improve the utility of the CPU and the speed of computer response to the user, several processes must be in memory, so that the transfer of data from / to main memory to / from the CPU can be efficient. But the capacity of the memory is not enough to save all parts of the process, the required memory settings so that the memory can be used as efficiently as possible.

Address Binding
A program is in the disk in the form of executable binary files. Programs must be brought into memory and inserted in a process that can be executed. At the time the program is placed in the memory it is necessary to add memory location address for the program.

Merger address with instruction and data memory addresses can occur when:

a.Compile Time
At compile time, can know the absolute address of the memory can be known before the execution, it can be done at the initial binding.

b.Load Time
If memory absolute address is unknown at compile time then the binding delayed until load time.

c.Execution Time
If an address change process for execution from one memory segment to another segment of the memory-binding postponed until run time (execution time).


Dynamic Loading

Dynamic loading is the placement of the parts is an important program or necessary to the memory. A routine will not be loaded into memory before it was called. All routine stored in the disk while the main programs loaded into memory and executed. The advantage of dynamic loading that the routine has not been used even if not loaded into memory.

Dynamic loading does not require special assistance from the operating system, only depending on the design of the program that created the user.

Dynamic Linking

The concept of dynamic linking with dynamic loading. Dynamic linking library system applies, which if all the programs in the system not to use this feature it will spend the disk and memory capacity for each program must duplicate libraries for each language included in its executable image. Stub is used as a reference library-routine in the image. Stub is a small program code that is used to indicate the exact location of the library-routine in the memory or a way to load the library if the routine does not exist.