Apparatus for JTAG-driven remote scanning

A microprocessor comprising:

• a plurality of functional units including one or more processor cores and a memory subsystem operatively connected to said one or more processor cores;
• a plurality of scan chains which interconnect respective sets of scan cells embedded in said functional units, said scan chains being controlled by an internal clock signal having a first frequency;
• a scan interface including a scan input and a scan output, said scan input and said scan output being controlled by an external clock signal having a second frequency which is slower than the first frequency;
• first transport logic which converts an input serial data stream at said scan input into input data packets, and selectively sends the input data packets to said scan chains using a transport protocol;
• and
• second transport logic which selectively receives output data packets from said scan chains using the transport protocol, and converts the output data packets into an output serial data stream at said scan output.