| 摘要 |
PURPOSE:To support high function instruction without complicating hardware by providing a space for instruction emulation and switching an instruction area according to whether or not the fetched instruction is an emulation object instruction. CONSTITUTION:Spaces 40 and 50 for emulation instruction are provided separately from the other macroinstruction spaces 41 and 51, constructed so as to switch the instruction area according to whether or not the fetched instruction is the emulation object instruction. In short, an undefined instruction code in the existing instruction set is applied to allocate a code for emulation object instruction to this, an instruction line is arranged on emulation instruction spaces 40 and 50 so as to emulate the emulation object instruction with the instruction line included in the existing instruction set or the like. Therefore, the instruction executed by a normal mode and the emulation instruction executed by the emulation mode can be decoded by a common instruction decoder. Thus, the high function instruction can be supported with simple configuration. |
