Error correction verification method and apparatus using CRC check remainders

An error correction system for rotating magnetic media, the error correction system comprising:

• a CRC generator/checker which generates CRC check remainder bytes by (1) using input data from a read sector to obtain regenerated CRC bytes for the read sector and (2) adding the regenerated CRC bytes to incoming CRC bytes of the read sector;
• a correction unit which generates error patterns for correcting errors in the read sector;
• a correction checker unit, responsive to the CRC check remainder bytes and the error patterns, for confirming that the error patterns accurately correct the errors in the read sector, wherein the correction checker unit comprises a first stage, and wherein the first stage includes:
• a register having a register input terminal and a register output terminal;
• a register input gate connected to control input to the register input terminal;
• a timing control gate which receives signals at least derived from the error patterns;
• an adder, the adder having a first input terminal connected to an output terminal of the timing control gate and a second input terminal connected to the register output terminal, an adder output terminal of the adder being connected to a first input terminal of the register input gate;
• a second input terminal of the register input gate being connected to receive the CRC check remainder bytes;
• a feedback multiplier connected between the register output terminal and a third input terminal of the register input gate.

An error correction method for rotating magnetic media, the error correction method comprising:

• generating CRC check remainder bytes by:
• a) using input data from a read sector to obtain regenerated CRC bytes for the read sector, and
• (b) adding the regenerated CRC bytes to incoming CRC bytes of the read sector;
• generating error patterns for correcting errors in the read sector;
• using the CRC check remainder bytes and the error patterns for confirming that the error patterns accurately correct the errors in the read sector by:
• (1) loading a predetermined number of the CRC check remainder bytes into a corresponding number of registers;
• (2) for each of a plurality of error patterns of the sector, adding the error pattern to the register having its CRC check remainder byte affected by the error pattern;
• (3) determining whether the contents of any of the registers indicates inaccurate correction of the errors.