PURPOSE: To perform fast processing by providing a control bit representing which emulation program out of plural emulation programs is executed.
CONSTITUTION: First and second emulation control programs(ECP) 20a, 20b provided between a native machine OS 10 and first and second emulation programs 23a, 23b issue an EXL(execute local) instruction to the emulation programs 23a, 23b. When the first emulation program 23a is executed, the content of an emulation state control bit register is controlled so as to be set at an off state, and when the second emulation program 23b is executed, the content of the emulation state control bit register is controlled so as to be set an on state. Instruction execution, interruption control, and a microprogram routine can be selected, respectively by using the control bit.
OHATA SHIGEKI
WATANABE KUNIHIKO
HITACHI ASAHI ELECTRON KK