Power supply and method for use in a computer system to confirm a save operation of the computer system and to stop a supply of power to the computer system after confirmation

• US 5,339,446 A
• Filed: 05/18/1993
• Issued: 08/16/1994
• Est. Priority Date: 12/26/1986
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Yuuichi, Yamasaki, Takuma
• Primary Examiner(s): Kriess, Kevin A.
• Application Number:
  US08/062,733
• Time in Patent Office: 455 Days
• Field of Search: 395/750, 395/800
• US Class Current: 713/340
• CPC Class Codes: G06F 1/24 Resetting means
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24

Abstract

A power supply for use in a computer system according to this invention has a one-chip microcomputer having a built-in A/D converter. The microcomputer, which has a communication function, performs a power off sequence for a computer system and a power off sequence for a hard disk drive built in the computer system, while communicating with the computer system. Further, the microcomputer detects the voltage and current of a chargeable battery, discriminates a low battery state, monitors a power switch, a hard disk drive switch and a reset switch, and monitors an input/output voltage.

Claims

1. A power supply system for use in a computer comprising:

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section having

coupling means for connecting said power control section to said computer system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation,

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal,

a low batter display section,

means for monitoring a voltage and a current of said battery, changing a reference voltage value in accordance with a detected current value, comparing a detected voltage value with said reference voltage value and causing said low battery display section to indicate a low battery when said detected voltage value is below said reference voltage value, and

means for dividing a level of said low battery into first through third sub-levels in accordance with said detected current value, causing said low battery display section to indicate said low battery upon detection of said first sub-level, sending said power off request signal to said computer system upon detection of said second sub-level, and outputting said power off signal to said power output section.

2. The power supply system according to claim 1, wherein said power output section includes

means for supplying power to said battery for a charging operation, and

wherein said power control section includes

a charge completion display section,

means for calculating a charged capacitance and a remaining capacitance of said battery and a charging time based on a value of a current flowing from said battery,

means for determining the completion of charging said battery from said calculated charged capacitance, remaining capacitance and charging time, and

means for causing said charge completion display section to indicate said completion of charging.

3. The power supply system according to claim 1, wherein said power output section includes

an AC adapter input voltage display section,

means for detecting an input voltage of said AC adapter, and

means for causing said AC adapter input voltage display section to indicate a voltage abnormality when said voltage abnormality occurs.

4. The power supply system according to claim 1, wherein said power output section includes

power switch means for indicating ON/OFF modes of power supply to a computer system assembly,

disk switch means for indicating ON/OFF modes of power supply to a disk drive, and

reset switch means for indicating a system initialization, and

wherein said power control section includes

means for detecting an ON or OFF signal from said power switch, disk switch and reset switch, and

means for outputting a signal to either supply power or inhibit the supply of power to said power output section.

5. The power supply system according to claim 1, wherein said power control section includes analog-to-digital converter means for converting voltage values and current values from said battery and said AC adapter into digital values.

6. The power supply system according to claim 1, wherein said computer system is a small size personal computer.

7. The power supply system according to claim 1, wherein said externally-supplied power off request signal is sent to said computer system when a power provided on said computer system is turned off.

8. The power supply system according to claim 1, wherein said externally-supplied power off request signal is sent to said computer system when a disk drive switch provided on said computer system is turned off.

9. The power supply system according to claim 1, wherein said externally-supplied power off request signal is sent to said computer system when power of said battery is below a predetermined value.

10. The power supply system according to claim 1, wherein said power control section includes means for informing said computer system of a battery'"'"'s remaining capacitance in response to a battery remaining capacitance check request from said computer system.

11. A method for cutting off a supply of power by a power supply system for use in a computer, the power supply system including a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage, and a power output section coupled to said power supply section, said power output section having a coupling for supplying power from said power supply section to said computer system and being responsive to a power off signal to inhibit the supply of all power to said computer system, the method comprising the steps of:

monitoring a voltage and a current of said battery;

changing a reference voltage value in accordance with a detected current value;

comparing a detected voltage value with said reference voltage value and causing a low battery display section to indicate a low battery when said detected voltage value is below said reference voltage value, the comparing step including the steps of

dividing a level of said low battery into first through third sub-levels in accordance with said detected current value,

causing said low battery display section to indicate said low battery upon detection of said first sub-level,

sending a power off request signal to said computer system upon detection of said second sub-level, and

outputting said power off signal to said power output section;

receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system;

receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation; and

transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal.

12. A power supply system for use in a computer having a main memory, registers and a battery backed-up random access memory (RAM), comprising:

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section having

coupling means for connecting said power control system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, the computer system saving at least contents of the main memory and the registers into the battery backed-up RAM in response to the system power off request signal, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation, and

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal.

13. The power supply system according to claim 12, wherein said power output section includes

means for supplying power to said battery for a charging operation, and

wherein said power control section includes

a charge completion display section,

means for calculating a charged capacitance and a remaining capacitance of said battery and a charging time based on a value of a current flowing from said battery,

means for determining the completion of charging said battery from said calculated charged capacitance, remaining capacitance and charging time, and

means for causing said charge completion display section to indicate said completion of charging.

14. The power supply system according to claim 12, wherein said power output section includes

an AC adapter input voltage display section,

means for detecting an input voltage of said AC adapter, and

means for causing said AC adapter input voltage display section to indicate a voltage abnormality when said voltage abnormality occurs.

15. The power supply system according to claim 12, wherein said computer system includes

power switch means for indicating ON/OFF modes of power supply to a computer system assembly,

disk switch means for indicating ON/OFF modes of power supply to a disk drive, and

reset switch means for indicating a system initialization, and

wherein said power control section includes

means for detecting an ON or OFF signal from said power switch, disk switch and reset switch, and

means for outputting a signal to either supply power or inhibit the supply of power to said power output section.

16. The power supply system according to claim 12, wherein said power control section includes analog-to-digital converter means for converting voltage values and current values from said battery and said AC adapter into digital values.

17. The power supply system according to claim 12, wherein said computer system is a small size personal computer.

18. The power supply system according to claim 12, wherein said externally-supplied power off request signal is sent to said computer system when a power provided on said computer system is turned off.

19. The power supply system according to claim 12, wherein said externally-supplied power off request signal is sent to said computer system when a disk drive switch provided on said computer system is turned off.

20. The power supply system according to claim 12, wherein said externally-supplied power off request signal is sent to said computer system when power of said battery is below a predetermined value.

21. The power supply system according to claim 12, wherein said power control section includes means for informing said computer system of a battery'"'"'s remaining capacitance in response to a battery remaining capacitance check request from said computer system.

22. A power supply system for use in a computer having a disk drive, comprising:

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section having

coupling means for connecting said power control section to said computer system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation,

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal, and

means for performing a disk drive power off sequence if said receiving means receives no acknowledgment signal during a predetermined period of time.

23. The power supply system according to claim 22, wherein said power output section includes

means for supplying power to said battery for a charging operation, and

wherein said power control section includes

a charge completion display section,

means for calculating a charged capacitance and a remaining capacitance of said battery and a charging time based on a value of a current flowing from said battery,

means for determining the completion of charging said battery from said calculated charged capacitance, remaining capacitance and charging time, and

means for causing said charge completion display section to indicate said completion of charging.

24. The power supply system according to claim 22, wherein said power output section includes

an AC adapter input voltage display section,

means for detecting an input voltage of said AC adapter, and

means for causing said AC adapter input voltage display section to indicate a voltage abnormality when said voltage abnormality occurs.

25. The power supply system according to claim 22, wherein said computer system includes

power switch means for indicating ON/OFF modes of power supply to a computer system assembly,

disk switch means for indicating ON/OFF modes of power supply to a disk drive, and

reset switch means for indicating a system initialization, and

wherein said power control section includes

means for detecting an ON or OFF signal from said power switch, disk switch and reset switch, and

means for outputting a signal to either supply power or inhibit the supply of power to said power output section.

26. The power supply system according to claim 22, wherein said power control section includes analog-to-digital converter means for converting voltage values and current values from said battery and said AC adapter into digital values.

27. The power supply system according to claim 22, wherein said computer system is a small size personal computer.

28. The power supply system according to claim 22, wherein said system power off request signal is sent to said computer system when a power provided on said computer system is turned off.

29. The power supply system according to claim 22, wherein said system power off request signal is sent to said computer system when a disk drive switch provided on said computer system is turned off.

30. The power supply system according to claim 22, wherein said externally-supplied power off request signal is sent to said computer system when power of said battery is below a predetermined value.

31. The power supply system according to claim 22, wherein said power control section includes means for informing said computer system of a battery'"'"'s remaining capacitance in response to a battery remaining capacitance check request from said computer system.

32. A power supply system for use in a computer comprising:

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

means including a microcomputer for charging the battery and for detecting completion of a charge operation when any of the following conditions is satisfied;

when the battery voltage drops from a peak value by a given value;

when a charged capacitance of the battery becomes 150%, provided that a nominal capacitance of the battery is 100%; and

when a charging time of the battery exceeds 10 hours.

33. The power supply system according to claim 32, wherein said power output section includes

means for supplying power to said battery for a charging operation, and wherein said power control section includes

a charge completion display section,

means for calculating a charged capacitance and a remaining capacitance of said battery and a charging time based on a value of a current flowing from said battery,

means for determining the completion of charging said battery from said calculated charged capacitance, remaining capacitance and charging time, and

means for causing said charge completion display section to indicate said completion of charging.

34. The power supply system according to claim 32, wherein said power control section includes

an AC adapter input voltage display section,

means for detecting an input voltage of said AC adapter, and

means for causing said AC adapter input voltage display section to indicate a voltage abnormality when said voltage abnormality occurs.

35. The power supply system according to claim 32, wherein said computer system includes

power switch means for indicating ON/OFF modes of power supply to a computer system assembly,

disk switch means for indicating ON/OFF modes of power supply to a disk drive, and

reset switch means for indicating a system initialization, and

wherein said power control section includes

means for detecting an ON or OFF signal from said power switch, disk switch and reset switch, and

means for outputting a signal to either supply power or inhibit the supply of power to said power output section.

36. The power supply system according to claim 32, wherein said power control section includes analog-to-digital converter means for converting voltage values and current values from said battery and said AC adapter into digital values.

37. The power supply system according to claim 32, wherein said computer system is a small size personal computer.

38. The power supply system according to claim 32, wherein an externally-supplied power off request signal is sent to said computer system when a power provided on said computer system is turned off.

39. The power supply system according to claim 32, wherein an externally-supplied power off request signal is sent to said computer system when a disk drive switch provided on said computer system is turned off.

40. The power supply system according to claim 32, wherein an externally-supplied power off request signal is sent to said computer system when power of said battery is below a predetermined value.

41. The power supply system according to claim 32, wherein said power control section includes means for informing said computer system of a battery'"'"'s remaining capacitance in response to a battery remaining capacitance check request from said computer system.

42. The power supply system according to claim 41, wherein said power control section includes means for detecting the completion of the charge operation after a predetermined period of time has elapsed from the charging operation.

43. A power supply system for use in a computer comprising:

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

controller means for automatically detecting a presence or absence of the AC adapter and the battery from a first reference voltage representing a driving voltage of the controller means, a second reference voltage representing a maximum voltage of the battery, and an analog input voltage input to the power control section such that the presence of both the AC adapter and the battery are detected when the analog input voltage is less than the second reference voltage, the absence of the AC adapter and the presence of the battery are detected when the analog input voltage is between the first reference voltage and the second reference voltage, and the presence of the AC adapter and the absence of the battery are detected when the analog input voltage is greater than or equal to the second reference voltage.

44. The power supply system according to claim 43, wherein said power output section includes

means for supplying power to said battery for a charging operation, and

wherein said power control section includes

a charge completion display section,

means for calculating a charged capacitance and a remaining capacitance of said battery and a charging time based on a value of a current flowing from said battery,

means for determining the completion of charging said battery from said calculated charged capacitance, remaining capacitance and charging time, and

means for causing said charge completion display section to indicate said completion of charging.

45. The power supply system according to claim 43, wherein said power control section includes

an AC adapter input voltage display section,

means for detecting an input voltage of said AC adapter, and

means for causing said AC adapter input voltage display section to indicate a voltage abnormality when said voltage abnormality occurs.

46. The power supply system according to claim 43, wherein said computer system includes

power switch means for indicating ON/OFF modes of power supply to a computer system assembly,

disk switch means for indicating ON/OFF modes of power supply to a disk drive, and

reset switch means for indicating a system initialization, and

wherein said power control section includes

means for detecting an ON or OFF signal from said power switch, disk switch and reset switch, and

means for outputting a signal to either supply power or inhibit the supply of power to said power output section.

47. The power supply system according to claim 43, wherein said power control section includes analog-to-digital converter means for converting voltage values and current values from said battery and said AC adapter into digital values.

48. The power supply system according to claim 43, wherein said computer system is a small size personal computer.

49. The power supply system according to claim 43, wherein an externally-supplied power off request signal is sent to said computer system when a power provided on said computer system is turned off.

50. The power supply system according to claim 43, wherein an externally-supplied power off request signal is sent to said computer system when a disk drive switch provided on said computer system is turned off.

51. The power supply system according to claim 43, wherein an externally-supplied power off request signal is sent to said computer system when power of said battery is below a predetermined value.

52. The power supply system according to claim 43, wherein said power control section includes means for informing said computer system of a battery'"'"'s remaining capacitance in response to a battery remaining capacitance check request from said computer system.

53. A portable computer system comprising:

a data processor assembly including,

a central processing unit,

program storage means for storing a program for controlling said central processing unit and a data processing result,

a backup memory, and

a disk drive;

a serial transmission path coupled to said data processor assembly;

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section having

coupling means for connecting said power control section to said computer system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation,

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal,

a low batter display section,

means for monitoring a voltage and a current of said battery, changing a reference voltage value in accordance with a detected current value, comparing a detected voltage value with said reference voltage value and causing said low battery display section to indicate a low battery when said detected voltage value is below said reference voltage value, and

means for dividing a level of said low battery into first through third sub-levels in accordance with said detected current value, causing said low battery display section to indicate said low battery upon detection of said first sub-level, sending said power off request signal to said computer system upon detection of said second sub-level, and outputting said power off signal to said power output section.

54. The system according to claim 53, wherein said data processor assembly includes means for, upon reception of said power off request signal from said power control section, causing said central processing unit to interrupt a currently running program, saving information necessary to continue said interrupted program to said backup memory, and returning said acknowledgment signal to said power control section.

55. The system according to claim 54, wherein said power control section includes means for waiting for said acknowledgment signal from said data processor assembly and for sending a time out signal to said data processor assembly and a control signal to said power output section when said acknowledgment signal is not received upon the elapse of a predetermined period of time, thereby stopping the supply of power to said disk drive.

56. A portable computer system comprising:

a data processor assembly including,

a central processing unit,

program storage means for storing a program for controlling said central processing unit and a data processing result,

a backup memory, and

a disk drive;

a serial transmission path coupled to said data processor assembly;

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

coupling means for connecting said power control section to said computer system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, the computer system saving at least contents of the program storage means into the backup memory in response to said system power off request signal, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation, and

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal,

57. The system according to claim 56, wherein said data processor assembly includes means for, upon reception of said power off request signal from said power control section, causing said central processing unit to interrupt a currently running program, saving information necessary to continue said interrupted program to said backup memory, and returning said acknowledgment signal to said power control section.

58. The system according to claim 57, wherein said power control section includes means for waiting for said acknowledgment signal from said data processor assembly and for sending a time out signal to said data processor assembly and a control signal to said power output section when said acknowledgment signal is not received upon the elapse of a predetermined period of time, thereby stopping the supply of power to said disk drive.

59. A portable computer system comprising:

a data processor assembly including,

a central processing unit,

program storage means for storing a program for controlling said central processing unit and a data processing result,

a backup memory, and

a disk drive;

a serial transmission path coupled to said data processor assembly;

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

coupling means for connecting said power control section to said computer system through a serial transmission path,

means including a microcomputer for detecting a degradation of said power supply section output voltage indicative of impending power failure, for receiving an externally-supplied power off request signal and subsequently transmitting a system power off request signal through said serial transmission path to command a save operation to be performed by said computer system, and for receiving an acknowledgment signal through said serial transmission path to confirm the completion of said save operation, and

means for transmitting said power off signal to said power output section to inhibit the supply of power through said power output section after receipt of said acknowledgment signal; and

means for performing a disk drive power off sequence if said receiving means receives no acknowledgment signal during a predetermined period of time.

60. The system according to claim 59, wherein said data processor assembly includes means for, upon reception of said power off request signal from said power control section, causing said central processing unit to interrupt a currently-running program, saving information necessary to continue said interrupted program to said backup memory, and returning said acknowledgment signal to said power control section.

61. The system according to claim 59, wherein said power control section includes means for waiting for said acknowledgment signal from said data processor assembly and for sending a time out signal to said data processor assembly and a control signal to said power output section when said acknowledgment signal is not received upon the elapse of a predetermined period of time, thereby stopping the supply of power to said disk drive.

62. A portable computer system comprising:

a data processor assembly including,

a central processing unit,

program storage means for storing a program for controlling said central processing unit and a data processing result,

a backup memory, and

a disk drive;

a serial transmission path coupled to said data processor assembly;

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

means including a microcomputer for charging the battery and for detecting completion of a charge operation when any of the following conditions is satisfied;

when the battery voltage drops from a peak value by a given value;

when a charged capacitance of the battery becomes 150%, provided that a nominal capacitance of the battery is 100%; and

when a charging time of the battery exceeds 10 hours.

63. The system according to claim 62, wherein said data processor assembly includes means for, upon reception of said power off request signal from said power control section, causing said central processing unit to interrupt a currently-running program, saving information necessary to continue said interrupted program to said backup memory, and returning a power off acknowledgment signal to said power control section.

64. The system according to claim 63, wherein said power control section includes means for waiting for said power off acknowledgment signal from said data processor assembly and for sending a time out signal to said data processor assembly and a control signal to said power output section when said power off acknowledgment signal is not received upon the elapse of a predetermined period of time, thereby stopping the supply of power to said disk drive.

65. A portable computer system comprising:

a data processor assembly including,

a central processing unit,

program storage means for storing a program for controlling said central processing unit and a data processing result,

a backup memory, and

a disk drive;

a serial transmission path coupled to said data processor assembly;

a power supply section comprising any of a battery and an AC adapter, said power supply section having an output voltage;

a power output section coupled to said power supply section and including

coupling means for supplying power from said power supply section to said computer system, and

means, responsive to a power off signal, for inhibiting the supply of all power to said computer system; and

a power control section including

controller means for automatically detecting a presence or absence of the AC adapter and the battery from a first reference voltage representing a driving voltage of the controller means, a second reference voltage representing a maximum voltage of the battery, and an analog input voltage input to the power control section such that the presence of both the AC adapter and the battery are detected when the analog input voltage is less than the second reference voltage, the absence of the AC adapter and the presence of the battery are detected when the analog input voltage is between the first reference voltage and the second reference voltage, and the presence of the AC adapter and the absence of the battery are detected when the analog input voltage is greater than or equal to the second reference voltage.

66. The system according to claim 65, wherein said data processor assembly includes means for, upon reception of said power off request signal from said power control section, causing said central processing unit to interrupt a currently-running program, saving information necessary to continue said interrupted program to said backup memory, and returning a power off acknowledgment signal to said power control section.

67. The system according to claim 66, wherein said power control section includes means for waiting for said power off acknowledgment signal from said data processor assembly and for sending a time out signal to said data processor assembly and a control signal to said power output section when said power off acknowledgment signal is not received upon the elapse of a predetermined period of time, thereby stopping the supply of power to said disk drive.