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.An apparatus for determining a sector location in a disk. A location circuit is configured to determine an angular location of a transducer head according to a selected index location on the disk. A memory is used to store a first value that corresponds to a selected angular distance along a selected track on the disk. An accumulator is configured to add the first value to the value of the content of the accumulator in response to an accumulator clock signal. A comparator is coupled to the location circuit and the accumulator to compare data related to the angular location and the content of the accumulator to generate a result. A generator is coupled to the comparator to provide a sector location signal in response to the result.

1. In a rotating disk data storage device of the type including a disk whereon data is written by a transducer head adjacent the disk in angularly extending sectors on concentric data tracks to be subsequently read therefrom by the transducer; a controller responsive to sector location pulses for locating said sectors; and means for moving the transducer head between tracks on the disk; an apparatus for providing the sector location pulses, comprising:
 master clock means synchronized with the rotation rate of the disk for providing master clock signals indicative of the angular location of the transducer head with respect to a selected index location on the disk following passage of the index location by the transducer head;    a first counter clocked by the clock means;    latch means for storing a selected time corresponding to a selected angular distance along a selected track on the disk;    an accumulator connected to the latch means for adding said selected time to the contents of the accumulator each time the accumulator is clocked by an accumulator clock signal;    a first comparator connected to the first counter and the accumulator for providing an electrical indication that the contents of the counter is at least as large as the contents of the accumulator;    accumulator clock means connected to the first comparator and responsive to said electrical indication for repetitively providing the accumulator clock signal to the accumulator so long as the accumulator contents does not exceed the first counter contents;    master reset means for resetting the first counter and the accumulator at such times that the index location on the disk passes the transducer head;    partial reset means for entering the selected time into the latch means and resetting the accumulator each time the transducer head is moved to a new track on the disk; and    sector location pulse generation means, connected to the first comparator, for providing the sector location pulses to the controller in response to at least selected ones of said electrical indications that the contents of the first counter is at least as large as the contents of the accumulator.    
     
     
       2. The apparatus of  claim 1  wherein the sector location pulse generation means comprises:
 a sector location pulse gate connected to the first comparator to receive said electrical indication of the relative contents of the first counter and the accumulator; and    means for generating a sector location pulse each time the sector location pulse gate is enabled;    
       wherein the apparatus further comprises:
 a second counter clocked by the accumulator clock signals;  
 a number of sectors latch for storing the numbers of sectors on the tracks of the disk; and  
 a second comparator connected to the second counter, the number of sectors latch and the sector location pulse gate for disabling the sector location pulse gate following attainment of the value stored in the number of sectors latch by the second counter.  
 
     
     
       3. The apparatus of  claim 2  wherein the latch means is further characterized as a means for storing a plurality of numbers corresponding to selected angular distances along a selected track of the disk and wherein the latch means comprises:
 a sector time latch for storing sector times corresponding to angular lengths of sectors on the tracks;    a delay time latch for storing delay times corresponding to selected angular skew distances of the sectors along tracks of the disk; and    an accumulation time selector connected between the accumulator and the sector and delay time latches for presenting sector times to the accumulator in an enabled state of the selector and for presenting the delay times to the accumulator in a disabled state of the selector whereby the selected time added to the contents of the accumulator in response to clocking of the accumulator by an accumulator clock pulse is a sector time at such times that the accumulation clock pulse occurs while the accumulation time selector is enabled and is a delay time at such times that the accumulator clock pulse occurs while the accumulation time selector is disabled; and    
       wherein the apparatus is further characterized as comprising delayed index controller means for disabling the accumulation time selector and the sector location pulse gate for the first accumulator clock signal following reset of the accumulator. 
     
     
       4. The apparatus of  claim 3  wherein the sector location pulse generation means comprises means for selecting the duration of the sector location pulses. 
     
     
       5. The apparatus of  claim 2  wherein the sector location pulse generation means comprises means for selecting the duration of the sector location pulses. 
     
     
       6. The apparatus of  claim 1  wherein the sector location pulse generation means comprises means for selecting the duration of the sector location pulses. 
     
     
       7. The apparatus of  claim 1  wherein the latch means is further characterized as a means for storing a plurality of numbers corresponding to selected angular distances along a selected track of the disk and wherein the latch means comprises:
 a sector time latch for storing sector times corresponding to angular lengths of sectors on the tracks;    a delay time latch for storing delay times corresponding to selected angular skew distances of the sectors along tracks of the disk; and    an accumulation time selector connected between the accumulator and the sector and delay time latches for presenting sector times to the accumulator in an enabled state of the selector and for presenting the delay times to the accumulator in a disabled state of the selector whereby the selected time added to the contents of the accumulator in response to clocking of the accumulator by an accumulator clock pulse is a sector time at such times that the accumulator clock pulse occurs while the accumulation time selector is enabled and is a delay time at such times that the accumulator clock pulse occurs while the accumulation time selector is disabled;    
       wherein the sector location pulse generation means comprises:
 a sector location pulse gate connected to the first comparator to receive said electrical indication of the relative contents of the first counter and the accumulator; and  
 means for generating a sector location pulse each time the sector location pulse gate is enabled; and  
 
       wherein the apparatus is further characterized as comprising delayed index controller means for disabling the accumulation time selector and the sector location pulse gate for the first accumulator clock signal following reset of the accumulator. 
     
     
       8. The apparatus of  claim 7  wherein the sector location pulse generation means comprises means for selecting the duration of the sector location pulses. 
     
     
       9. A method for generating sector location pulses for locating data storage sectors on data tracks of a rotating disk data storage device having a transducer head adjacent the surface of a rotating disk for writing to and reading from the data storage sectors, comprising the steps of:
 maintaining a continuous count of a time from index following passage of a selected index location on the disk by the transducer head;    maintaining an accumulation of sector times, each sector time equal to the time required for a data storage sector to pass the transducer head along a selected track, following passage of the index location by the transducer head;    adding a sector time to said accumulation of sector times each time the time from index attains a value at least as large as the accumulation of sector times;    generating a sector location pulse each time the time from index attains a value at least as large as the accumulation of sector times;    setting the accumulation of sector times to zero each time the transducer head is moved to a new track on the disk; and    repetitively accumulating sector times following movement of the transducer head to a new track on the disk until the accumulation of sector times exceeds the time from index.    
     
     
       10. The method of  claim 9  further comprising the steps of:
 maintaining a count of the number of sectors which have reached the transducer head following passage of the index location by the transducer head at such times that the transducer head is positioned adjacent a selected track on the disk;    discontinuing generation of sector location pulses at such times that the number of the sectors that have passed the transducer head reaches a preselected number of sectors for the selected track; and    following movement of the transducer to a new track on the disk, updating the number of sectors count to an effective number of passed sectors between the index location and the location of the transducer head on the new track.    
     
     
       11. The method of  claim 10  further comprising the step of accumulating a delayed index time to be added to the accumulation of sector times each time the index location on the disk passes the transducer head. 
     
     
       12. The method of  claim 11  wherein the step of generating a sector location pulse is further characterized as generating a sector location pulse having one of a plurality of durations selected for each track on the disk. 
     
     
       13. The method of  claim 9  further comprising the step of accumulating a delayed index time to be added to the accumulation of sector times each time the index location on the disk passes the transducer head and each time the transducer head is moved to a new track on the disk. 
     
     
       14. The method of  claim 13  wherein the step of generating a sector location pulse is further characterized as generating a sector location pulse having one of a plurality of durations selected for each track on the disk. 
     
     
       15. The method of  claim 9  wherein the step of generating a sector location pulse is further characterized as generating a sector location pulse having one of a plurality of durations selected for each track on the disk. 
     
     
       16. A method for determining a location of a sector for use with a hard disk assembly having at least one hard disk for storing digital information and a circuit configured to detect an index signal generated at a predetermined angular orientation of said disk, comprising:
   positioning a transducer head over a first track having a first number of sectors;        detecting a first index signal while the transducer head is positioned over the first track;        positioning the transducer head over a second track having a second number of sectors different than the first number of sectors;        reading a sector time related to a time it takes for a data storage sector to pass the transducer head along the second track;        determining an angular location of the transducer head relative to the predetermined angular orientation while the transducer head is positioned over a first sector in the second track; and        determining at least partly from the angular location of the transducer head and the sector time, the location of the next sector to pass under the transducer head before the occurrence of a second index signal.     
     
     
       17. The method as defined in  claim 16 , further comprising clocking a counter in proportion to a disk rotation rate, wherein the counter count is used to determine the angular location of the transducer head relative to the predetermined angular orientation. 
     
     
       18. The method as defined in  claim 16 , further comprising maintaining an accumulation based on the sector time. 
     
     
       19. The method as defined in  claim 18 , further comprising:
   comparing data related to the angular location of the transducer head with data related to the accumulation; and        selectively continuing to accumulate said sector time based at least partly on said comparison.     
     
     
       20. The method as defined in  claim 18 , further comprising:
   comparing data related to the angular location of the transducer head with data related to the accumulation; and        generating a sector location signal based at least partly on said comparison.     
     
     
       21. The method as defined in  claim 18 , further comprising resetting the accumulation to a predetermined value when the transducer head is moved to a new track on the disk having a different number of sectors than the previous track. 
     
     
       22. A method for locating data storage sectors on a magnetic drive have at least one disc with a plurality of tracks, comprising:
   positioning a transducer head over a first track having a first number of sectors;        receiving a first index signal related to an index location;        positioning the transducer head over a second track having a second number of sectors different than the first number of sectors;        determining the position of the transducer head relative to the index location based at least in part on the first index signal; and        locating a first sector in the second track before an occurrence of a second index signal based at least in part on a length of a sector in the second track and the position of the transducer relative to the index location.     
     
     
       23. The method as defined in  claim 22 , further comprising:
   accumulating a value related to the length of a sector in the second track;        comparing data related to an angular position of the transducer head relative to the index location with data related to the accumulation of the value; and        generating a sector location signal based at least partly on said comparison.     
     
     
       24. The method as defined in  claim 23 , further comprising:
   maintaining a count of the number of sectors which have reached the transducer following passage of the index location by the transducer when the transducer is positioned over the second track; and        discontinuing generation of sector location signals when the number of sectors that have passed the transducer reaches a pre - selected number of sectors.     
     
     
       25. The method as defined in  claim 23 , further comprising:
   maintaining a count of the number of sectors which have reached the transducer following passage of the index location by the transducer when the transducer is positioned over the second track; and        following movement of the transducer to a new track on the disk, updating the count of the number of sectors to an effective number of passed sectors between the index location and the location of the transducer on the new track.     
     
     
       26. The method as defined in  claim 23 , wherein generating a sector location signal is further characterized as generating a sector location signal having one of a plurality of durations, wherein the first track is associated with a first sector location signal duration and the second track is associated with a second sector location signal duration. 
     
     
       27. A method for determining a location of a sector of a disk, comprising:
   positioning a transducer head over a first track having a first number of sectors;        detecting a first index signal;        positioning the transducer head over second track having a second number of sectors;        reading a sector time related to a time it takes for a sector to pass the transducer head along the second track;        determining an angular location of the transducer head while it is positioned over a first sector in the second track; and        determining the location of a next sector to pass under the transducer head before an occurrence of a second index signal.     
     
     
       28. The method of  claim 27  wherein the first and second number of sectors are different. 
     
     
       29. The method of  claim 28  wherein the angular location is relative to a predetermined angular orientation. 
     
     
       30. The method of  claim 28  further comprising clocking a counter in proportion to a disk rotation rate. 
     
     
       31. The method of  claim 30  wherein the counter is used to determine the angular location. 
     
     
       32. The method of  claim 27  further comprising maintaining an accumulation based on the sector time. 
     
     
       33. A method for locating data storage sectors, comprising:
   positioning a transducer over a first track having a first number of sectors;        receiving a first index signal related to an index location;        positioning the transducer over a second track having a second number sectors;        determining a position of the transducer based on the first index signal; and        locating a first sector in the second track before an occurrence of a second index signal.     
     
     
       34. The method of  claim 33  wherein the second index signal is based on a length of a sector in the second track and a position of the transducer relative to the index location. 
     
     
       35. A rotating disk data storage device, including a disk whereon data is intended to be written in sectors on data tracks to be subsequently read therefrom by a transducer, wherein at least a first track has a first number of sectors and at least a second track has a second number of sectors, comprising:
   a location circuit synchronized with the rotation rate of the disk, the location circuit configured to determine the angular location of the transducer head with respect to a selected index location on the disk;        a memory used to store a first value corresponding to a selected angular distance along a selected track on the disk;        an accumulator circuit connected to the memory, wherein the accumulator adds the first value to the contents of the accumulator in response to an accumulator clock signal;        a first comparator connected to the location circuit and the accumulator, wherein the first comparator is configured to compare data related to the angular location of the transducer head with the contents of the accumulator and generate corresponding comparison results; and        a sector location signal generator circuit coupled to the first comparator, wherein the sector location signal generator circuit is configured to provide sector location signals in response to at least selected ones of said comparison results.     
     
     
       36. The rotating disk data storage device as defined in  claim 35 , wherein the location circuit includes a clock generation circuit which generates a clock signal synchronized with the rotation rate of the disk, further comprising a counter clocked by the clock signal. 
     
     
       37. The rotating disk data storage device as defined in  claim 36 , further comprising a reset circuit configured to reset the counter to a first value at least partly in response to determining that the index location on the disk passed the transducer head. 
     
     
       38. The rotating disk data storage device as defined in  claim 36 , further comprising a reset circuit configured to reset the accumulator circuit to a first value at least partly in response to determining that the index location on the disk passed the transducer head. 
     
     
       39. The rotating disk data storage device as defined in  claim 36 , further comprising a reset circuit configured to set the accumulator circuit to a first value at least partly in response to moving the transducer from a first track to a second track. 
     
     
       40. A circuit for generating sector location signals used to locate data storage sectors on data tracks of a rotating disk data storage device having a transducer head adjacent the surface of a rotating disk for writing to and reading from the data storage sectors located on disk tracks, wherein at least a first track has a first number of sectors and at least a second track has a second number of sectors, comprising:
   a location circuit disk configured to determine the angular location of the transducer head with respect to a first reference location;        a first memory configured to store a plurality of values related to sector lengths associated with corresponding tracks; and        a sector location signal generation circuit configured to generate a sector location signal at least partially based on the value associated with the sector length for the track over which the transducer head is being positioned and the angular location of the transducer head with respect to the first reference location.     
     
     
       41. The circuit as defined in  claim 40 , further comprising:
   a second memory used to store a value corresponding to a selected angular distance along a selected track on the disk; and        an accumulator connected to the memory, wherein the accumulator is configured to repeatedly add the selected time to the contents of the accumulator in response to a first signal.     
     
     
       42. The circuit as defined in  claim 40 , further comprising a comparator connected to the location circuit and the accumulator, wherein the first signal is selectively generated in response to a first comparison result generated by the comparator. 
     
     
       43. The circuit as defined in  claim 40 , further comprising a sector location signal generator connected to the comparator, the sector location signal generator configured to selectively generate sector signals at least partly in response to comparison results of a first type. 
     
     
       44. An apparatus comprising:
   a location circuit configured to determine an angular location of a transducer head according to a selected index location on a disk;        a memory used to store a first value corresponding to a selected angular distance along a selected track on the disk;        an accumulator configured to add the first value to a content of the accumulator in response to an accumulator clock signal;        a first comparator coupled to the location circuit and the accumulator to compare data related to the angular location and the content and generate a result; and        a generator coupled to the first comparator to provide a sector location signal in response to the result.     
     
     
       45. The apparatus of  claim 44  wherein the location circuit includes a clock circuit which generates a clock signal. 
     
     
       46. The apparatus of  claim 45  further comprising a counter clocked by the clock signal. 
     
     
       47. The apparatus of  claim 46  further comprising a reset circuit configured to reset one of the counter and the accumulator to a first value when the index location passed the transducer head. 
     
     
       48. The apparatus of  claim 46  further comprising a reset circuit configured to reset the accumulator when the transducer head in response to moving the transducer from a first to second track. 
     
     
       49. An apparatus comprising:
   a location circuit configured to determine an angular location of a transducer head;        a first memory configured to store a value related to a sector length associated with a track of a disk; and        a generator configured to generate a sector location signal base on the value associated with the sector length for a track over which the transducer head is being positioned and the angular position of the transducer head.     
     
     
       50. The apparatus of  claim 49 , further comprising:
   a second memory configured to store a selected time to corresponding to a selected angular distance along a selected track on the disk; and        an accumulator having a content coupled to the memory, wherein the accumulator is configured to add the selected time to the content in response to a first signal.     
     
     
       51. The apparatus of  claim 50 , further comprising a comparator coupled to the location circuit and the accumulator to generate a result. 
     
     
       52. The apparatus of  claim 51 , wherein the first signal is selectively generated in response to the result. 
     
     
       53. A system comprising:
   an interface coupled to a computer to receive information;        a controller coupled to the interface to control read/write information on a disk having a surface;        a transducer head adjacent to the surface for writing to and reading from a sector located on a disk, and        a device configured to locate the sector on the disk, the device comprising:      a location circuit configured to determine an angular location of the transducer head;        a first memory configured to store a value related to a sector length associated with a track of the disk; and        a generator configured to generate a sector location signal base on the value associated with the sector length for track over which the transducer head is being positioned and the angular position of the transducer head.       
     
     
       54. The system of  claim 53 , further comprising:
   a second memory configured to store a selected time to corresponding to a selected angular distance along a selected track on the disk; and        an accumulator having a content coupled to the memory, wherein the accumulator is configured to add the selected time to the content in response to a signal.     
     
     
       55. The system of  claim 54 , further comprising a comparator coupled to the location circuit and the accumulator to generate a result.