Address translation:

• Compiler time: If it is known in advance that a program will reside at a particular location of primary memory, and then the compiler can be told to make the object code with complete addresses right away. For instance, the boot sect in a bootable disk can be compiled with the starting point of code set to 007C:0000.
• Load time: It is very rare that we already know the location a program will be assigned ahead of its execution. In mostly cases, the compiler has to generate reloadable code with logical addresses. Therefore the address translation can be performed on the code at the load time. Above figure shows that a program is loaded at location x. If the complete program resides on a monolithic block, then every memory reference can be translated to be physical by added to x.

               An Example of fixed partitioning of a 64-Megabyte memory