Patent ID: 7490271

Claim:
A semiconductor device comprising: a first chip as an object of tracing and having a data processing circuit mounted thereon; a second chip having a storage circuit storing data used by said first chip mounted thereon; and a third chip monitoring a signal between said first chip and said second chip and tracing an operation of said first chip, and formed by a chip separate from said first and second chips, wherein said third chip is connected directly to at least one of the first and second chips; wherein said semiconductor device is a stacked type multichip package having said first, second and third chips mounted in a height direction; wherein said third chip includes a sample pad inserted between a wiring between said first and second chips, a trace circuit monitoring a signal flowing through the sample pad and controlling tracing of said first chip, a first storage circuit successively storing the signal flowing through the sample pad as trace information, and an external input/output port externally outputting the trace information stored in said first storage circuit and externally receiving data as an input for setting of said trace circuit; and wherein said trace circuit includes a trace point register storing a memory address to be monitored, a comparing circuit comparing an address flowing through said sample pad with the memory address stored in said trace point register, and a control circuit controlling progress of tracing based on a result of comparison by said comparing circuit.