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An IEEE 1149.5 module test and maintenance (MTM) bus slave module interface core is presented, which is used for direct access from the system bus to the IEEE 1149.1 chip-level or on-chip buses to facilitate hierarchical system test and diagnosis. The hierarchical test methodology also is presented, which is applicable to the system-on-chip environment, All the standard 1149.1 instructions, such as SAMPLE/PRELOAD, EXTEST, BYPASS, and even RUNBIST, can be performed within three 1149.5 read/write-data message cycles. The messages are transmitted between the MTM-bus master module (Ill-module) and the slave module (S-module). We adopt the full test access port control method to activate the 1149.1 boundary-scan paths via the 1149.5 MTM-bus. Our S-module interface circuit implements 16 CORE commands and one read/write-data command. It has been prototyped using a field-programmable gate array chip and implemented by a full-custom chip. Hierarchical test of multiple 1149.1 compatible boards has been experimentally verified.