Abstract:
The concept of the invention is to format any bit stream which is to be recorded into a succession of data blocks, each of which corresponds lengthwise to at least the length of the largest defect statistically known to exist in the surface. The data blocks are grouped into data segments, with each data segment (1) being of a length corresponding to no more than the minimum length statistically known to exist between defects and (2) comprising (at least) two less data blocks (which shall be hereinafter sometimes referred to as "vacant blocks") than may be accommodated within a data segment. By sensing, during a writing operation, whether data is being effectively written in the magnetic surface in question, any data which fails to get written may be rewritten by utilizing the vacant data blocks: one block per segment will inherently contain "defective" information, and another block thereof will be, per the invention, adapted to record a low frequency flag signal to identify the occurrence of a rewrite operation. Because each data segment is no greater than the minimum spacing between defects, there can be only one defect per segment and, attendantly, the aforementioned rewriting operation may be implemented.