Abstract: As fast and powerful commodity processors have been developed, it has become practical to emulate on platforms built using commodity processors the proprietary legacy hardware systems of powerful older computers. High performance is often a key requirement for a system even when built using emulation software. Within the hardware of the legacy system the memory management software and paging hardware is often complex, and takes considerable code in the software emulator to emulate. If the segments of data referenced by a program running under the software emulator can be placed in contiguous linear memory, the memory management software and the work of the software emulator can be reduced to improve performance and reduce complexity of the emulated system.

Abstract: This invention relates to the art of computer system emulation and, more particularly, to a computer system emulator in which the functions normally performed by the hardware in a legacy central processor unit are emulated by a software program. The invention is to enhance the emulated instruction set beyond that of the legacy machine such to include as new single instructions a method for invoking operating system functions, with the machine coding of the operating system functions now being performed by machine code native to the new host machine, rather than as a sequence of emulated legacy instructions.