Access to floppy disk stack

Claim 2

In a mass storage flexible disk file containing multiple flexible storage disks rotating coaxially in a spaced stack configuration, said stack receiving ventilation fluid internally to replenish ambient fluid expelled from between said disks by centrifugal action, the pressure of said received fluid being variable to cause storage surfaces of said disks to rotate alternatively in distinct first and second states of axial displacement equilibrium, said states serving respectively to inhibit and support formation of a circumferentially uniform auto-sustaining split suitable for storage transducing access at any axial coordinate position in said stack when said stack is transiently disturbed at said position, the method of quickly and precisely aligning a source of said transient disturbance with a target coordinate position in said stack prior to formation of said circumferentially uniform split comprising: while said ventilation pressure is controlled to retain said surfaces in said first state of equilibrium, applying an external disturbance at a selected trial position in said stack estimated to coincide with said target coordinate but subject to imprecise determination due to varying motion of the eges of the disks interfacing at said target coordinate; said disturbance forming and sustaining a partial split having circumferentially irregular shape at said trial position; said partial split being unsuited for storage transducing access; determining location of said partial split relative to said target coordinate by using a widened portion of said partial split as a relatively stable positional reference for distinguishing said relative location; when said trial position coincides with said target coordinate position varying the pressure of said ventilation fluid to form said auto-sustaining split at said target coordinate position; and when said trial and target positions do not coincide, shifting the position of said external disturbance incrementally until said trial and target positions do coincide and then excecuting said above-mentioned pressure varying step to form said auto-sustaining split.

Claim 3

In a mass storage disk file containing multiple flexible storage disks rotating coaxially in a spaced stack configuration, said stack being supplied with ventilation fluid internally which replenishes ambient fluid expelled from between said disks by centrifugal action, the pressure of said ventilation fluid being variable to condition surfaces of said disks alternatively to distinct first and second states of axial displacement equilibrium, said states serving respectively to inhibit and support formation of a circumferentially uniform auto-sustaining split suitable for storage transducing access at any pre-selected target axial coordinate position in said stack when said stack is transiently disturbed at said position in association with a variation in said pressure, the method of estabilishing a said circumferentially uniform split precisely and quickly at a said target position comprising: applying a disturbance externally at a selected (trial) axial position in said stack while said surfaces are in said first (inhibiting) state of displacement equilibrium; said trial position being either coincident with said target position or offset slightly therefrom due to variations in disk thickness and varying motion of edges of said disks tending to make determination of said target position inherently imprecise; said disturbance forming and sustaining a partial split at said trial position, said partial split having circumferentially irregular shape unsuited for storage transducing access but forming much more quickly than said auto-sustaining split; determining offset of said trial position relative to said target position by using a wide portion of said partial split as a relatively unvarying positional reference in said stack; depending upon whether said offset determining step respectively indicates coincidence (null offset) or non-coincidence between said trial and target positions selectively performing a respective one of the following steps: a. upon coincidence generating an indication of said coincidence; b. upon non-coincidence correctively shifting the position of said disturbance relative to said stack, in predetermined increments of displacement and in a direction suitable for reducing the offset, and repeating said steps of determining and selectively performing; and in response to said indication of coincidence, varying said ventilation fluid pressure to condition said surfaces to said second state of displacement equilibrium while sustaining said disturbance; thereby causing said auto-sustaining split to form at the target position.

Claim 4

In a mass storage disk file containing multiple flexible storage disks rotating coaxially in a spaced stack configuration, said stack being supplied with ventilation fluid internally which replenishes ambient fluid expelled from between said disks by centrifugal action, the pressure of said ventilation fluid being variable to condition surfaces of said disks alternatively to distinct first and second states of axial displacement equilibrium, said states serving respectively to inhibit and support formation of a circumferentially uniform auto-sustaining split suitable for storage transducing access at any pre-selected target axial coordinate position in said stack when said stack is transiently disturbed at said position in association with a variation in said pressure, the method of estabilishing a said circumferentially uniform split precisely and quickly at a said target position comprising: applying a disturbance externally at a selected (trial) axial position in said stack while said surfaces are in said first (inhibiting) state of displacement equilibrium; said trial position being either coincident with said target position or offset slightly therefrom due to variations in disk thickness and varying motion of edges of said disks tending to make determination of said target position inherently imprecise; said disturbance forming and sustaining a partial split at said trial position, said partial split having circumferentially irregular shape unsuited for storage transducing access but forming much more quickly than said auto-sustaining split; determining offset of said trial position relative to said target position by using a wide portion of said partial split as a relatively unvarying positional reference in said stack; depending upon whether said offset determining step respectively indicates coincidence (null offset) or non-coincidence between said trial and target positions selectively performing a respective one of the following steps: a. upon coincidence generating an indication of said coincidence; b. upon non-coincidence correctively shifting the position of said disturbance relative to said stack, in predetermined increments of displacement and in a direction suitable for reducing the offset, and repeating said steps of determining and selectively performing; and in response to said indication of coincidence, varying said ventilation fluid pressure to condition said surfaces to said second state of displacement equilibrium while sustaining said disturbance; thereby causing said auto-sustaining split to form at the target position.

Claim 5

The method of claim 2 including the step following said ventilation pressure varying step of: terminating said disturbance.

Claim 6

The method of claim 2 wherein said disturbance is produced by: directing a focused jet of said ambient fluid under pressure radially into said trial position.

Claim 7

The method of claim 4 wherein said jet is confined to a small arc section of the rotational ambit of said stack and said offset determining step is accomplished by: sensing progressively differentiated indicia on edges of disks passing to one side of and abutting said partial split.

Claim 8

The method of claim 2 wherein said predetermined increment of corrective shifting is less than the space between consecutive said disks in an unsplit and undisturbed configuration.

Claim 9

The method of claim 2 wherein said determining step is accomplished by sensing progressively differentiated indicia on edges of disks passing to one side of and abutting said partial split at said wide portion of said partial split.

Claim 10

The method of claim 7 wherein said sensing of indicia is carried out relative to indicia picked up diffusely from a group of plural adjacent said disks on said one side of said partial split.

Claim 11

The method of claim 7 wherein said indicia are pulse burst manifestations which are angularly staggered on successive said disks so as to be individually sensible without overlap and wherein bursts on successive disks contain different numbers of discrete pulse manifestations varied in a predetermined progression throughout said stack to provide said progressive differentiation.

Claim 12

In a mass storage flexible disk file containing multiple flexible storage disks rotating coaxially in a spaced stack configuration, said stack receiving ventilation fluid under varied pressure which replenishes ambient fluid expelled from between said disks by centrifugal action, and which also conditions displaceable storage surfaces of said disks alternatively to distinct first and second states of displacement equilibrium, said states serving respectively to inhibit and support formation of a circumferentially uniform auto-sustaining split suitable for storage transducing access at any selected target axial coordinate position of said stack when said stack is transiently disturbed at said position, apparatus for precisely and quickly verifying correct alignment of a source of said transient disturbance with said target position before forming said split comprising: means for positioning a said source of disturbance in alignment with a trial position estimated to coincide with said target position; means effective to jointly condition said ventilation fluid pressure to a condition associated with said first equilibrium state, and said source to a condition for sustainably disturbing said stack to produce a partial split at said trial position having circumferentially irregular form; means for detecting a relatively unvarying wide portion of said partial split; means coupled to said detecting means for determining the offset of said trial position relative to said target position; and means conditioned upon said determination of offset for alternatively effecting: a. generation of indication of position coincidence when said offset has null magnitude; and b. otherwise initiating coordinated further iterative operation (of said positioning means, said detecting means, said offset determining means and said alternative effecting means) to re-locate said partial split closer to said target position, in re-locational increments sufficiently small to avoid the possibility of overshooting the target position.

Claim 13

In a mass storage flexible disk file containing multiple flexible storage disks rotating coaxially in a spaced stack configuration, said stack receiving ventilation fluid under varied pressure which replenishes ambient fluid expelled from between said disks by centrifugal action, and which also conditions displaceable storage surfaces of said disks alternatively to distinct first and second states of displacement equilibrium, said states serving respectively to inhibit and support formation of a circumferentially uniform auto-sustaining split suitable for storage transducing access at any selected target axial coordinate position of said stack when said stack is transiently disturbed at said position, apparatus for precisely and quickly verifying correct alignment of a source of said transient disturbance with said target position before forming said split comprising: means for positioning a said source of disturbance in alignment with a trial position estimated to coincide with said target position; means effective to jointly condition said ventilation fluid pressure to a condition associated with said first equilibrium state, and said source to a condition for sustainably disturbing said stack to produce a partial split at said trial position having circumferentially irregular form; means for detecting a relatively unvarying wide portion of said partial split; means coupled to said detecting means for determining the offset of said trial position relative to said target position; and means conditioned upon said determination of offset for alternatively effecting: a. generation of indication of position coincidence when said offset has null magnitude; and b. otherwise initiating coordinated further iterative operation (of said positioning means, said detecting means, said offset determining means and said alternative effecting means) to re-locate said partial split closer to said target position, in re-locational increments sufficiently small to avoid the possibility of overshooting the target position.

Claim 14

Apparatus in accordance with claim 10 including: means responsive to said coincidence indication for successively controlling said ventilation fluid pressure to produce said second equilibrium state and controlling said source to terminate said disturbance.

Claim 15

Apparatus in accordance with claim 10 wherein said source comprises means for controllably emitting a stream of said ambient fluid, confined both axially and circumferentially in alignment relative to said trial and relocational positions.

Claim 16

Apparatus in accordance with claim 10 wherein edges of successive said disks contain progressively differentiated indicia and said detecting means includes means for distinguishing the indicia on the edge of a disk facing a predetermined side of said partial split.

Claim 17

Apparatus in accordance with claim 13 wherein said distinguishing means comprises a sensing head configured to receive indicia from edges of plural said disks and means coupled to said head for logically processing said indicia to effect precise discrimination of the indicia contained on said facing disk.

Claim 18

Apparatus according to claim 14 wherein said indicia comprise pulse burst manifestations progressively staggered at different non-overlapping angle sectors of successive disks and arranged in progressively differentiatable configurations on successive disks.

Claim 19

Apparatus according to claim 15 wherein bursts on successive said disks have different numbers of pulses, the numbers differing in a predetermined numerical progression.