Abstract: A wrapper architecture has a parent core A and a child core B. The parent core A comprises scan chains (70), wrapper input cells (71), wrapper output cells (74) and a parent TAM, PTAM [0:2]. Likewise, the child core comprises scan chains (76), wrapper input cells (75) and wrapper output cells (72), and is connected to a child TAM, CTAM [0:2]. Each wrapper input cell (75) and each wrapper output cell (72) of the child core is adapted to be connected to the parent TAM, PTAM, in addition to being connected to the child TAM, CTAM, thereby enabling the child core to be placed in the In-test and Ex-test modes at the same time, and allowing the parent and child cores to be tested in parallel.

Abstract: An electronic circuit has a plurality of sub-circuits. Clock gate circuits supply gated clock signals to data storage elements of the sub-circuits. The clock gate circuits have gate inputs for receiving gate signals that commands blocking passage of the clock signal. Data can be transferred between data storage elements between two of the subcircuits. A detector circuit flags invalid data in the data storage element of the second one of the sub-circuits. The detector circuit has a flag storage element arranged to set a flag when the clock gate circuit of the second one of the sub-circuits passes the clock signal for the second one of the sub-circuits after the clock gate of the first one of the sub-circuits has blocked the clock signal for the first one of the sub-circuits. The flag indicates the relative phase of the clocks signals of different sub-circuits when the clocks are stopped. The flag is used to invalidate data in the data storage element of the second one of the sub-circuits.