Hard sectoring circuit and method for a rotating disk data storage device

Abstract

An apparatus for providing sector location pulses to a controller of a rotating disk data storage device having a counter clocked in proportion to the disk rotation rate and an accumulator for accumulating times to sectors on the disk. A comparator connected to the counter and the accumulator enables an accumulator clock for repetitive clocking of the accumulator at such times the contents of the accumulator do not exceed the contents of the counter. A sector location pulse generator connected to the comparator generates the controller pulses, when enabled, concurrently with the accumulator clock signals. A master reset generator resets the first counter and the accumulator each time an index location on the disk passes a transducer head used to read and write data to and from the disk and a partial reset generator resets the accumulator each time the transducer head is moved between tracks on the disk. The sector location pulse generator includes a flip-flop that is set following a partial reset signal to prevent sector location pulses from being generated following partial reset until the accumulator has accumulated the count in the counter.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates generally to improvements in rotating disk magnetic data storage devices, and, more particularly, but not by way of limitation to improvements in locating data sectors on the disks of such devices.2. Brief Description of the Prior ArtIn rotating disk magnetic data storage devices, data is stored in sectors extending angularly along concentric data tracks defined on the disks of the device. The disks have magnetizable surface coatings. Data is written and subsequently read by transducer heads that fly over the surfaces of the disks to magnetize cells of the surface coating, for writing, or respond to differences in magnetization of adjacent cells for reading. Both operations are controlled by a read / write controller that provides encoded data to the transducer head during writing and receives emf pulses from the transducer heads during readback of the data.For such a system to operate, it is necessary f...

AI Technical Summary

Problems solved by technology

The use of address marks on a disk suffers from the disadvantage that the marks can be lost for any of a number of reasons; for example, through flaws in the magnetic medium in which the data is written or accidental turn on of a write gate, used to enable writing, as a transducer head passes over an address mark.

That sector's data can never be retrieved because the controller will never receive the pulses necessary for locating the sector.

Similarly, read errors while searching for the address mark may cause a sector to be missed and lower the throughput of the data storage device.

The problem is exacerbated by other requirements placed on a rotating disk data storage system.

As a result, it has been necessary in the past to either forego recording tracks at different frequencies or use address marks, despite the disadvantage of much lower data security.

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