ADRESSERINGSKRETS AVSEDD FOR EN DATOR, VARS MINNESREGISTER ER FORDELADE PA OLIKA OMRADEN

摘要

A means for automatically changing from a first to a second processor state register (PSR) when the relative address represented by the base value contained in the first of the PSR's does not fall within first predetermined limits. Logic means respond to such limits test failure to automatically switch active PSR's and recompute the absolute address using the base value contained in the other second PSR, followed by another limits test using second predetermined limits. When both limits tests fail a guard mode bit is tested which, if clear, will permit execution of the instruction outside the predetermined limits. When a jump instruction is involved, the switch of PSR's is made permanent until the occurrence of the next jump instruction requiring an automatic switching of PSR's.