No special hardware is required in the host; a simple bidirectional I/O pin is sufficient.
In other words, the increasing complexity of today's software and hardware designs is leading to some fresh approaches to debugging.
Silicon manufacturers offer more and more on-chip debugging features for emulation of new processors.
Users want to debug their application program under conditions that imitate the actual setup of their system.
Because of that, the capability to debug a user program in an actual target system is required.
Examples include: Depending on the target part, the BDM controller may feature a hardware breakpoint register.