Alternate access mechanism for saving and restoring state of read-only register

摘要

The present invention relates to a method and apparatus for restoring a status data in a computer system. The circuit comprises: a read-only register for storing a read-only status value during a normal mode of operation; a first data path for supplying the read-only status value; a first control signal path for supplying a first control signal for controlling writing the supplied read-only status value into the read-only register during the normal mode of operation, the stored read-only status value being saved into a save area prior to removing power from the read-only register; a second data path for subsequently re-supplying from the save area the previously stored read-only status value; a second control signal path for supplying a second control signal for controlling restoration of the re-supplied read-only status value into the read-only register during a restore mode of operation; and circuitry coupling the first and second data and control signal paths to the read-only register to facilitate the writing during the normal mode of operation and the restoration during the restore mode of operation.