Apparatus for detecting and correcting data transfer errors of a magnetic disk system

An apparatus for detecting and correcting errors which occur when transferring individual sectors of data between a magnetic disk and a main memory of a magnetic disk system comprising:

• a data transfer interface disposed on a transfer path connecting said magnetic disk and said main memory, for successively transferring said individual sectors of data between said magnetic disk and said data transfer interface during a first period of time, and for successively transferring said individual sectors of data between said data transfer interface and said main memory during a second period of time to write and read said individual sectors of data, said first period of time being at least twice as long as said second period of time, creating a free time period between the end of said second period of time and the end of said first period of time;
• check data generation means operatively connected to said transfer path for successively generating original check data for said individual sectors of data and for affixing said original check data to said individual sectors of data at times when said individual sectors are written to said magnetic disk;
• error detection means operatively connected to said transfer path and to said check data generation means for generating an error signal indicating detection of an error sector in response to a difference between said original check data and said affixed check data for any of said individual sectors of data at times when said error sectors are read from said magnetic disk;
• and
• error correction means responsive to send error signal for transferring said error sector from said main memory to said error correction means during a first said free time, and for correcting said error sector in accordance with said original check data and said affixed data to transfer a corrected said error sector from said error correction means to said main memory during a second said free time.