公开(公告)号：CA1182575A

公开(公告)日：1985-02-12

申请号：CA424283

申请日：1983-03-23

Applicant: IBM

Inventor： BEAN GEORGE H ,  GUM PETER H

IPC: G06F9/46 ,  G06F9/455 ,  G06F9/48

Abstract: The embodiment switches an address in a prefix register in a CPU of a MP or UP data processing system from one PSA (program save area) to another PSA. The prefix address switching changes the control of the CPU from a preferred guest SCP (system control program) to a host SCP. This switching is done by hardware/ microcode means which is not controllable by user instructions executable on the CPU. This manner of CPU control switching obtains for a preferred guest SCP (such as MVS/370) operating in relation to a host SCP (such as VM/370) nearly the efficiency of standalone execution on the CPU by a preferred guest SCP that is the same as a standalone version of the guest SCP.