supervisor call instruction การใช้

• This was accomplished using an MVS emulator that intercepted system calls at the Supervisor Call instruction ( SVC ) level.
• Most access to supervisor services is via system subroutines that issue the necessary Supervisor Call instructions ( SVCs ) rather than by direct use of SVCs.
• In the IBM System / 360 mainframe family, a Supervisor Call instruction implements a system call for legacy facilities; the Program Call ( PC ) instruction is used for newer facilities.
• The fact that and double-increment the program counter before pushing it to the stack facilitates the technique of treating them as supervisor call instructions, as found on some mainframe computers.
• Indeed, the OS has a special facility for " fast fixing " these short-term fixed data buffers ( fixing which is performed without resorting to a time-consuming Supervisor Call instruction ).
• In addition, privileged code can temporarily make an address space unswappable With a SYSEVENT Supervisor Call instruction ( SVC ); certain changes in the address space properties require that the OS swap it out and then swap it back in, using SYSEVENT TRANSWAP.
• When first implemented in CP / CMS release 3.1, this use of DIAG provided an operating system interface that was analogous to the System / 360 Supervisor Call instruction ( SVC ), but that did not require altering or extending the system's virtualization of SVC.
• Typically such macros expand into executable code, e . g ., for the EXIT macroinstruction, a list of " define constant " instructions, e . g ., for the DCB macro, or a combination of code and constants, with the details of the expansion depending on the parameters of the macro instruction ( such as a reference to a file and a data area for a READ instruction ); he executable code often terminated in either a " branch and link register " instruction to call a routine, or a supervisor call instruction to call an operating system function directly.