Microcomputer for accessing a memory outside the chip by using an address generated from the CPU

摘要

An external bus I/F section has a function in which, when a bus access is requested by an instruction execution section, high-order several bits of a logical address generated by a CPU are outputted from an output terminal to the outside of a chip, as a space identifier for indicating which of an integrated ROM space, an integrated RAM space, and the external space is accessed by a currently executed program. A part of an address generated by the CPU is used so that the space which is accessed by the currently executed program is known from the outside in real time without requiring an external hardware.