Explain the working of a loader in the linking process.

A loader in the linking process loads the executable code into memory for execution by the CPU.

The loader is a crucial component of an operating system that prepares a program to be run by loading it into the computer's memory. It is the part of the operating system that is responsible for loading executable files from the disk into the main memory of the computer. This process is essential for the execution of any program.

The loader's role begins after the linker has combined individual object files produced by a compiler into a single executable file. The loader takes this executable file, which is in a format that the operating system can understand, and loads it into memory. This involves reading the binary instructions from the file and placing them in the correct locations in memory.

The loader also performs other important tasks. It resolves symbolic references between object modules, allocates memory for the program's variables, and sets up the stack and the heap, which are areas of memory used for dynamic memory allocation. The loader also prepares the program counter, which is a register in the CPU that holds the memory address of the next instruction to be executed.

Once the loader has finished its work, the operating system starts the program running by passing control to the loaded code. The CPU then begins executing the program's instructions, which are now in memory.

In some systems, the loader also handles relocation, which involves adjusting the absolute addresses in the program so that it can be loaded at different locations in memory. This is necessary because the memory location where the program is loaded may not be known at compile time.

In summary, the loader plays a vital role in the linking process. It takes the executable file produced by the linker, loads it into memory, and prepares it for execution by the CPU. Without the loader, the computer would not be able to run any programs.