The devices implement the standard IEEE 1149.1 JTAG ⁽¹⁾interface for in-circuit based debug. Additionally, the devices support real-time mode of operation allowing modification of the contents of memory, peripheral, and register locations while the processor is running and executing code and servicing interrupts. The user can also single step through non-time-critical code while enabling time-critical interrupts to be serviced without interference. The device implements the real-time mode in hardware within the CPU. This is a feature unique to the 28x family of devices, requiring no software monitor. Additionally, special analysis hardware is provided that allows setting of hardware breakpoint or data/address watch-points and generating various user-selectable break events when a match occurs. These devices do not support boundary scan; however, IDCODE and BYPASS features are available if the following considerations are taken into account. The IDCODE does not come by default. The user must go through a sequence of SHIFT IR and SHIFT DR state of JTAG to get the IDCODE. For BYPASS instruction, the first shifted DR value would be 1.