| 摘要 |
PURPOSE:To control a main storage access based on the result of a comparison, by providing a protection key also to a base register that is used when an access is given to a main storage and thus carrying out a comparison among the protection key, a protection key in a program state word and a main storage key. CONSTITUTION:A protection key PK1 is provided in a program state word PSW exisiting in a CPU, and a protection key RK2 and an address RA3 to receive an access are provided in a pace register. In addition, a main storage ket 4 and a storage region M corresponding to the key 4 are provided to the main storage. Then a comparison is carried out by a comparator 17 between a protection key PK10 in the program state word and the protection key RK having page register No.11 within an instruction register. Furthermore a comparison is given in a comparator 19 with the coincidence result obtained from a comparison through the comparator 17 between the key PK10 and the storage key MK of index number 12. Based on the 1st and 2nd results of comparison, a control is given to a main storage access circuit 22 that uses the data from the main storage for an input. Thus the storage of a main storage 30 is protected effectively. |
