JOHN CHRISTOPHER KELLEY, M.S.
Psychologist at Fathom Cir, Austin, TX

6895530, May 17, 2005

Jan 24, 2003

10/350658

William C. Moyer - Dripping Springs TX, US
John Kelley - Austin TX, US

Freescale Semiconductor, Inc. - Austin TX

G06F011/00

714 25, 714 27

A data processing system () includes a debug unit () that is capable of providing unobtrusive debug capabilities to the normal operation of the data processing system by controlling activation of all or a selected subset of a plurality of subsystems as needed for a debug operation. For example, power can be conserved by activating selected subsystems as needed for a debug operation. Furthermore, in one embodiment, the debug unit provides a level of activation, ranging from deactivation to full activation, to the selected subsystems which provides further control of the data processing system. In one embodiment, debug control and status registers () are provided for power management handshaking between the debug unit and the plurality of subsystems. The handshaking can be used to ensure that a debug operation may proceed properly since the selected subsystems are capable of providing status information to the debug unit.