System Service Program

system service program Supports and provides the services for other program. System service program perform Varity of tasks.  They are further divided into three portions

i) Linkage Editor: A service routine that converts the output of assemblers and compilers into a form that can be loaded and executed.

To link together separately assembled programs. You may code and assemble a number of subprograms separately and link-edit these subprograms into one executable program. The linkage editor enables data in one subprogram to be recognized in another and facilitates transfer of control between subprograms at execution time. The linking process is usually automatically done by a linker or binder program that searches a set of libraries and other modules in a given order.

ii) Librarian: it is a program that performs all the functions of I/O devices. it has the task of storing programs on the disk, maintain the directory and security of user files.

iii) Input/output control system: the function of this program is to check all the hardware of the computer. The physical operations including accessing of disk ports , checking the states of desired ports etc.