Abstract: A disk sequencer, which is loaded with control words from a format table and a frame number associated with the first control word loaded, automatically cycles through loaded control words and finds a control word that corresponds to the current position of a data sector. The disk sequencer includes a first counter that is initialized according to a frame number read from a servo sector or according to an index mark and incremented for each end-of-servo pulse so that the first counter accurately indicates the current position of a data head to a data frame granularity. A second counter is loaded with a data frame number associated with the control words, and the second counter is incremented each time the last control word for a data frame is discarded. For automatic alignment, the disk sequencer cycles through and discards control words until comparison of the counts in the two counters indicates the control words are properly aligned.

Abstract: A disk sequencer uses control words to identify starts and splits in headerless data sectors. Each control word indicates an event-count, an initial event, and a terminal event. The initial event, which can be an EOS pulse, a sector pulse, or a data sync pulse, synchronizes the start of a count until the terminal event. The terminal event causes either generation of a sector pulse indicating a start of a data sector or an interrupt indicating a split in a data sector. A disk sequencer includes an event counter and a data segment sequencer. The event counter starts counting at the initial event, counts the event-count, and generates the sector pulse or interrupt at the end of the event-count. A sector pulse starts a data segment sequencer processing a first data segment of a data sector. The interrupt causes the data segment sequencer to execute an interrupt routine for fields surrounding a servo sector.