Loader resides in main memory under all situations in resident - OS computer - Operating System

Q.  What must reside in the main memory under all situations in a resident - OS computer?
- Published on 19 Oct 15

a. Linker
b. Loader
c. Assembler
d. Compiler

ANSWER: Loader


  • Nirja Shah   -Posted on 12 Nov 15
    - It is the part of an operating system that is responsible for loading programs and libraries.

    - It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution.

    - Loading a program involves tasks such as reading the contents of the executable file containing the program instructions into memory, and then carrying out other required preparatory tasks to prepare the executable for running.

    - The operating system starts the program by passing control to the loaded program code once the loading process is completed.

    - All operating systems that support program loading have loaders, apart from highly specialized computer systems that only have a fixed set of specialized programs.

    - Embedded systems typically do not have loaders, and instead the code executes directly from ROM.

    - In order to load the operating system itself, as part of booting, a specialized boot loader is used.

    - It is a permanent resident in memory, although some operating systems that support virtual memory may allow the loader to be located in a region of memory that is pageable.

    - The operating systems that support virtual memory, the loader may not actually copy the contents of executable files into memory, but rather may simply declare to the virtual memory subsystem that there is a mapping between a region of memory allocated to contain the running program's code and the contents of the associated executable file.

    - The virtual memory subsystem is then made aware that pages with that region of memory need to be filled on demand if and when program execution actually hits those areas of unfilled memory.

    - The program's code are not actually copied into memory until they are actually used, and unused code may never be loaded into memory at all.

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