SIMULATION SYSTEM OF VIRTUAL COMPUTER

PURPOSE:To increase the simulation processing speed for an SSK instruction given from an operating system using a shared segment, by providing a step to decide whether a virtual main memory address is equal to an address in a shared main memory. CONSTITUTION:A register number is extracted out of an operand part of an SSK instruction 2 to give addresses to corresponding registers 3 and 4. The virtual address of the register 3 is converted into a real address by a segment table 5 and a page table 7 to obtain a memory block 12 on a main memory. It is checked whether a shared segment bit 16 in a segment table entry 6 is turned on or not. If the bit 16 is off, i.e., a private segment exists instead of a shared segment, the contents of a main memory key 4 are set to a key area 13 on the block 12. At the same time, only the key part of the key 4 is preserved at a KEY table 8. While no operation is performed in case a shared segment is decided. Thus the SSK instruction processing is finished.