All The Claims

1. A disk drive comprising:
(a) a disk;
(b) an actuator arm;
(c) a head connected to a distal end of the actuator arm;
(d) a voice coil motor (VCM) comprising a voice coil, the VCM for rotating the actuator arm about a pivot to actuate the head radially over the disk; and
(e) a VCM driver comprising:
an H-bridge driver comprising a plurality of driver switches for driving current from a supply voltage through the voice coil to ground;
a first sense resistor connected in series between the supply voltage and at least one of the driver switches;
a first amplifier for amplifying a voltage across the first sense resistor to generate a first sense signal;
a second sense resistor connected in series between at least one of the driver switches and ground;
a second amplifier for amplifying a voltage across the second sense resistor to generate a second sense signal;
a first oscillator for generating a first frequency signal in response to the first sense signal;
a second oscillator for generating a second frequency signal in response to the second sense signal; and
a first counter responsive to a reference frequency, the first frequency signal, and the second frequency signal, wherein an output of the first counter represents a current flowing through the voice coil.
2. The disk drive as recited in claim 1, wherein the output of the first counter represents a difference between the reference frequency and the first and second frequency signals.
3. The disk drive as recited in claim 1, wherein the VCM driver further comprises pulse width modulated (PWM) circuitry responsive to the output of the first counter for generating a PWM signal for controlling the driver switches.
4. The disk drive as recited in claim 3, wherein:
(a) current flows through the first sense resistor and the voice coil while the PWM signal is in a first state;
(b) current flows through the second sense resistor and the voice coil while the PWM signal is in a second state;
(c) the first counter is responsive to the first frequency signal while the PWM signal is in the first state and to the second frequency signal while the PWM signal is in the second state;
(d) the VCM driver further comprises a second counter responsive to at least the first frequency signal while the PWM signal is in the second state; and
(e) an output of the second counter is used to cancel an offset in the measured current flowing through the voice coil.
5. The disk drive as recited in claim 4, wherein the output of the second counter is used to adjust the first and second sense signals.
6. The disk drive as recited in claim 4, wherein the first counter comprises:
(a) a first up counter responsive to the first frequency signal while the PWM signal is in the second state, the first up counter for counting the number of periods in the first frequency signal over a period of the PWM signal;
(b) a first down counter responsive to the first frequency signal, wherein an output of the first up counter is loaded into the first down counter;
(c) a second up counter responsive to the second frequency signal while the PWM signal is in the first state, the second up counter for counting the number of periods in the second frequency signal over a period of the PWM signal;
(d) a second down counter responsive to the second frequency signal, wherein an output of the second up counter is loaded into the second down counter; and
wherein an output of the first down counter and an output of the second down counter are combined to generate the output of the first counter in order to compensate for a difference between the operating characteristics of the first and second oscillators.
7. A method of operating a disk drive, the disk drive comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, a voice coil motor (VCM) comprising a voice coil for rotating the actuator arm about a pivot to actuate the head radially over the disk, and an H-bridge driver comprising a plurality of driver switches for driving current from a supply voltage through the voice coil to ground, the method comprising the steps of:
amplifying a voltage across a first sense resistor to generate a first sense signal, the first sense resistor being connected in series between the supply voltage and at least one of the driver switches;
amplifying a voltage across a second sense resistor to generate a second sense signal, the second sense resistor being connected in series between at least one of the driver switches and ground;
generating a first frequency signal in response to the first sense signal;
generating a second frequency signal in response to the second sense signal;
counting periods in the reference frequency, the first frequency signal, and the second frequency signal, to generate a first count representing a current flowing through the voice coil.
8. The method as recited in claim 7, wherein the first count represents a difference between the reference frequency and the first and second frequency signals.
9. The method as recited in claim 7, further comprising the step of generating a PWM signal for controlling the driver switches in response to the first count.
10. The method as recited in claim 9, wherein:
current flows through the first sense resistor and the voice coil while the PWM signal is in a first state;
current flows through the second sense resistor and the voice coil while the PWM signal is in a second state;
the first count is generated in response to the first frequency signal while the PWM signal is in the first state and to the second frequency signal while the PWM signal is in the second state;
the method further comprises the steps of:
(a) counting periods in at least the first frequency signal while the PWM signal is in the second state to generate a second count; and
(b) canceling an offset in the measured current flowing through the voice coil in response to the second count.
11. The method as recited in claim 10, further comprising the step of adjusting the first and second sense signals in response to the second count.
12. The method as recited in claim 10, wherein the step of generating the first count comprises the steps of:
(a) counting up periods in the first frequency signal while the PWM signal is in the second state to generate a third count, wherein the counting up occurs over a period of the PWM signal;
(b) loading the third count into a first down counter for counting down periods in the first frequency signal to generate a fourth count;
(c) counting up periods in the second frequency signal while the PWM signal is in the first state to generate a fifth count, wherein the counting up occurs over a period of the PWM signal;
(d) loading the fifth count into a second down counter for counting down periods in the second frequency signal to generate a sixth count; and
(e) combining the fourth and sixth count to generate the first count.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A compound semiconductor device containing a hetero junction bi-polar transistor comprising a sub-collector layer, a collector layer, a base layer and an emitter layer formed as thin film crystal layers in this turn on a compound semiconductor substrate by vapor growth wherein the ratio of current gainbase sheet resistance of the hetero junction bi-polar transistor is not less than 0.60.

1. An apparatus for the lifting and transportation of ferromagnetic metal sheets, the apparatus comprising:
magnetic retaining means for retaining the ferromagnetic metal sheet; and
lifting and carrying means for facilitating the transportation of the ferromagnetic metal sheet.
2. The apparatus of claim 1, further comprising means for releasing the ferromagnetic metal sheet from said magnetic retaining means.
3. An apparatus for the lifting and transportation of ferromagnetic metal sheets, the apparatus comprising:
a flame operable for bearing the load of the ferromagnetic metal sheet; and
a plurality of permanent magnets disposed about the load bearing side of said frame, the magnets being configured to collectively provide adequate force to retain the ferromagnetic metal sheet onto said frame when said frame and the ferromagnetic metal sheet are being transported.
4. The apparatus of claim 3, wherein the magnetic poles of said plurality of permanent magnets are arranged in a North-South-North pattern of magnetic fields along the length or breadth of said frame.
5. The apparatus of claim 3, further comprising means for releasing the ferromagnetic metal sheet from said plurality of permanent magnets.
6. The apparatus of claim 3, further comprising at least one force-imparting mechanical device joined to said frame that is operable for imparting a bending force upon the ferromagnetic metal sheet retained by said plurality of permanent magnets, the force being applied at particular points on the ferromagnetic metal sheet to thereby induce a curvature in the ferromagnetic metal sheet that increases the distance between the ferromagnetic metal sheet and at least one of said plurality of permanent magnets.
7. The apparatus of claim 6, wherein said at least one force-imparting mechanical device is selected from the group of force-imparting devices consisting of cams, wheels, levers, offset devices, rods, and springs.
8. The apparatus of claim 6, wherein said at least one force-imparting mechanical device comprises a lever having a cylindrical roller or wheel at the force-imparting end of the lever.
9. The apparatus of claim 6, wherein at least two of said force-imparting mechanical devices are mechanically linked together such that two or more of said force-imparting devices are engaged and disengaged together.
10. The apparatus of claim 6, further comprising means for locking said at least one force-imparting mechanical device into a safety position to prevent engagement during transportation of the retained ferromagnetic metal sheet.
11. The apparatus of claim 6, wherein said at least one force-imparting mechanical device is mechanically actuated pneumatically, hydraulically, electrically, or magnetically.
12. The apparatus of claim 3, wherein said frame is adjustable in length andor breadth.
13. The apparatus of claim 3, wherein at least one of said plurality of permanent magnets includes a magnetizing material selected from the group consisting of ferrite, rare earth, and alnico magnets.
14. The apparatus of claim 3, wherein at least one of said plurality of permanent magnets is removably joined to said frame.
15. The apparatus of claim 3, wherein the position of at least one of said plurality of permanent magnets is adjustable relative to said frame or relative to any other of said at least one of said plurality of permanent magnets.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1-21. (canceled)
22. An apparatus, comprising:
logic to be coupled to multiple memory devices;
the logic to select, in response, at least in part, to at least one received command, at least one memory device set that is comprised in the multiple memory devices for an operation that is to involve the at least one memory device set;
the at least one received command to include one or more fields that permit the at least one memory device set to be indicated in the at least one received command in terms of one or more of the following: one or more individual memory devices in the multiple memory devices, one or more multiple memory device groups in the multiple memory devices, one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
23. The apparatus of claim 22, wherein:
the one or more fields permit deselection of at least one other memory device set that is comprised in the at least one memory device set; and
the one or more fields also permit a configuration setting to be selected for the at least one memory device set.
24. The apparatus of claim 22, wherein:
the one or more fields permit one or more sizes of the multiple memory device groups to be selectable; and
the one or more fields include one or more groups of bits that permit the at least one memory device set to be indicated in terms of any of the following: the individual memory devices in the multiple memory devices, the one or more multiple memory device sets in the multiple memory devices, the one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
25. The apparatus of claim 22, wherein:
the at least one received command comprises a single command that indicates the at least one memory device set and also includes configuration information to be provided to the at least one memory device set; and
the one or more fields permit the at least one received command to indicate, as the at least one memory device set, any desired subset of the multiple memory devices.
26. The apparatus of claim 22, wherein:
the at least one received command comprises a command sequence that includes a selection command to select the at least one memory device set, an operation command to perform the operation, and data for use in completing the command sequence.
27. The apparatus of claim 22, wherein:
the apparatus further comprises a memory controller to issue the at least one command to the logic via a memory bus;
the one or more fields are to be presented simultaneously via the bus; and
the one or more memory modules comprise one or more dual inline memory modules.
28. A method, comprising:
selecting, by logic to be coupled to multiple memory devices, in response, at least in part, to at least one received command, at least one memory device set that is comprised in the multiple memory devices for an operation that is to involve the at least one memory device set;
the at least one received command to include one or more fields that permit the at least one memory device set to be indicated in the at least one received command in terms of one or more of the following: one or more individual memory devices in the multiple memory devices, one or more multiple memory device groups in the multiple memory devices, one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
29. The method of claim 28, wherein:
the one or more fields permit deselection of at least one other memory device set that is comprised in the at least one memory device set; and
the one or more fields also permit a configuration setting to be selected for the at least one memory device set.
30. The method of claim 28, wherein:
the one or more fields permit one or more sizes of the multiple memory device groups to be selectable; and
the one or more fields include one or more groups of bits that permit the at least one memory device set to be indicated in terms of any of the following: the individual memory devices in the multiple memory devices, the one or more multiple memory device sets in the multiple memory devices, the one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
31. The method of claim 28, wherein:
the at least one received command comprises a single command that indicates the at least one memory device set and also includes configuration information to be provided to the at least one memory device set; and
the one or more fields permit the at least one received command to indicate, as the at least one memory device set, any desired subset of the multiple memory devices.
32. The method of claim 28, wherein:
the at least one received command comprises a command sequence that includes a selection command to select the at least one memory device set, an operation command to perform the operation, and data for use in completing the command sequence.
33. The method of claim 28, wherein:
a memory controller issues the at least one command to the logic via a memory bus;
the one or more fields are presented simultaneously via the bus; and
the one or more memory modules comprise one or more dual inline memory modules.
34. Machine-readable memory containing instructions that when executed by a machine result in performing of operations comprising:
selecting, by logic to be coupled to multiple memory devices, in response, at least in part, to at least one received command, at least one memory device set that is comprised in the multiple memory devices for an operation that is to involve the at least one memory device set;
the at least one received command to include one or more fields that permit the at least one memory device set to be indicated in the at least one received command in terms of one or more of the following: one or more individual memory devices in the multiple memory devices, one or more multiple memory device groups in the multiple memory devices, one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
35. The machine-readable memory of claim 34, wherein:
the one or more fields permit deselection of at least one other memory device set that is comprised in the at least one memory device set; and
the one or more fields also permit a configuration setting to be selected for the at least one memory device set.
36. The machine-readable memory of claim 34, wherein:
the one or more fields permit one or more sizes of the multiple memory device groups to be selectable; and
the one or more fields include one or more groups of bits that permit the at least one memory device set to be indicated in terms of any of the following: the individual memory devices in the multiple memory devices, the one or more multiple memory device sets in the multiple memory devices, the one or more memory modules in the multiple memory devices, and all of the multiple memory devices.
37. The machine-readable memory of claim 34, wherein:
the at least one received command comprises a single command that indicates the at least one memory device set and also includes configuration information to be provided to the at least one memory device set; and
the one or more fields permit the at least one received command to indicate, as the at least one memory device set, any desired subset of the multiple memory devices.
38. The machine-readable memory of claim 34, wherein:
the at least one received command comprises a command sequence that includes a selection command to select the at least one memory device set, an operation command to perform the operation, and data for use in completing the command sequence.
39. The machine-readable memory of claim 34, wherein:
a memory controller is to issue the at least one command to the logic via a memory bus;
the one or more fields are to be presented simultaneously via the bus; and
the one or more memory modules comprise one or more dual inline memory modules.