DECIDING SYSTEM OF VIRTUAL SHIFT MODE

摘要

PURPOSE:To decide easily a virtual shift mode of a computer by initializing a memory area which receives an access in a virtual shift mode with the data different from that of a memory area which receives no access. CONSTITUTION:The address given from an instruction is equal to Yen0F (Yen: 16-notation number) together with the value of an index register is equal to Yen01. Under such conditions, the physical address of a memory 1 to receive an access is equal to the sum Yen10. Then the initialized value '1' is obtained with the data given from the memory 1. In a virtual shift mode the accesses are given to the values Yen00-Yen0F obtained by lapping around the value obtained by adding the value of a virtual shift pointer to said sum value. Then '-1' is initialized as the value of the memory 1. Thus the virtual shift mode is known.