Emulation techniques giving necessary information to a microcomputer to perform software debug and system debug even for incomplete target system

摘要

An emulation apparatus is capable of setting conditions to be noticed in a programmable manner, and includes a programmable output circuit having a timing detection circuit for detecting establishment of the set conditions on referring to information and the like on an emulation bus, and data storage groups for outputting data previously stored in a programmable manner, corresponding to the condition detected by the circuit. A part of output information of the programmable output circuit is capable of being selected by a selection circuit to be supplied, instead of output information of the corresponding portion of a user's system, to a microcomputer for emulation. The programmable output circuit includes a delay circuit for delaying the output data and effectively emulates I/O ports of the target machine.