Dynamic mask-ROM register patching

According to one embodiment of the present invention, a method of tuning a Power-On-Reset (POR) register in a data storage device comprises determining a tuned value for the POR register using feedback from the data storage device obtained during a certification process of the data storage device and storing a list in one or more system sectors of the data storage device, the list comprising an address of the POR register to be patched and the tuned value. According to another embodiment of the present invention, a disc drive comprises a rotatable disc, a microprocessor, and a memory. The memory has a start-up routine that, when executed by the microprocessor, causes the microprocessor to patch a Power-On-Reset (POR) register using a tuned values stored in one or more system sectors of the rotatable disc.