I suppose you mean a so called
embedded software.
Some of their IDSes (
integrated development systems) indeed contain debugging possibilities like code / registers / tracing / watching / breakpoints. I remember few years ago, at some funny laboratories, I had the opportunity to deal with BIOS debugging (till that moment I thought BIOS debuggers don't exist
). We faced two approaches. One was MS Windows IDE (!) based debugger connected to the second machine via COM port. The second debugger was embeeded into... the BIOS itself. There was some shell command to call the debugger (in any moment) and, if I remember correctly, a hotkey.
It was AMI or AWARD bios (it didn't have any specific name). I bet you will find some information in Google.
Good luck.