A system for receiving Joint Task Action Group (JTAG) data bits from a
device under test includes a deserializer that receives serial messages
from the device under test and forms data frames based on the serial
messages. A frame sync module communicates with the deserializer and
forms JTAG data bits based on the data frames. N virtual JTAG test access
ports (VTAPs), each having an input and an output. The N VTAPs are
connected in a daisy chain and the input of a first VTAP receives the
JTAG data bits from the frame sync module.