MICROCOMPUTER, ELECTRONIC EQUIPMENT AND EMULATION METHOD

摘要

PROBLEM TO BE SOLVED: To obtain a microcomputer, electronic equipment and an emulation method capable of realizing an optimum evaluation environment while saving the number of terminals. SOLUTION: An external bus 28 is shared by an external memory 30 and an emulation memory 32, and in an emulation mode, an access to an internal ROM 16 of a CPU 12 is switched to an access to the memory 32. The ON/OFF operation of the emulation mode is switched by a mode selection terminal or a mode selection register. The memory 32 is controlled by a control signal CNT2 different from a control signal CNT1 for the memory 30. A memory read signal in the CNT2 is activated at timing earlier than that of a memory read signal in the CNT1 so that the fetching and decoding of an instruction are completed within one clock cycle. The mode selection terminal selects each mode booted from the internal ROM 16 or the external memory 30 or an OPT mode.