Error-tolerant target-sector search using previous n sector id for high-speed cd

Abstract

An optical disk controller reads CD-ROM disks at high speeds that commonly produce errors. Errors in the headers that identify sectors are tolerated by the sector-search hardware. The disk-controller firmware writes a virtual target register the previous sector's header's minutes, seconds, frame (MSF), which is one less that the desired sector's MSF, or MSF-1. A physical target that precedes the virtual target is searched for. The physical target precedes the desired sector by N sectors, so that the physical target is MSF-N. When the physical target matches a header read from the disk, a good sector found flag is set. The physical target is then incremented for each new sector and compared to the virtual target. Once the physical target matches the virtual target, the following sector is buffered to the host. The raw header from the disk is stored and error corrections are made using the error correction byte following the sector's data. The corrected raw header is compared to the virtual target to determine if the correct sector was captured. The virtual target is also incremented so that all following sectors that are transferred to the host can also have their headers checked.