Methods for diagnosing malfunctions in a disk drive

DETAILED DESCRIPTION The present invention concerns methods used in disk drives for diagnosing malfunctions in the path by which data passes to and from the disk.
The disk drive in which the methods of the present invention are used has control apparatus including a microprocessor and memory for the microprocessor, memory for temporarily holding data being transferred to and from the disk, and a read-write processor for encoding data codes to produce disk codes and decoding disk codes to produce data codes.
The disk further contains tracks reserved solely for diagnostic operations.
In a first diagnostic method, the microprocessor makes a copy of a test pattern stored in the microprocessor memory and provides it to the memory used to transfer data.
The test pattern is then provided to the read-write processor, which translates it to disk codes and outputs it to a diagnostic track on the disk.
The read-write processor then reads the translated disk codes and translates them into data codes.
The translated data codes are provided to the memory used to transfer data.
The microprocessor receives the translated data codes from the memory used to transfer data and compares them with the original test pattern.
If they are different, there is a malfunction in the read-write processor or in the path between the read-write processor and the disk.
In a second diagnostic method, the read-write processor includes a data path by which disk codes translated from data codes may be provided to the read-write processor without being written to or read from the disk drive.
As described above, data codes which are copies of a test pattern are provided to the memory which transfers data.
The read-write processor then translates the data codes to disk codes and receives the disk codes again via the data path just described.
The read-write processor then retranslates the disk codes to data codes and outputs the retranslated data codes to the memory which transfers data.
The retranslated data codes are compared with the test pattern as described above