Browse Prior Art Database

Automatic DISK POWER Reduction for Portable Computers

IP.com Disclosure Number: IPCOM000036282D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Edrington, J: AUTHOR [+5]

Abstract

Disclosed is hardware and software which reduce the power consumed by a fixed disk subsystem, by turning power to the disk off after an idle period and restoring power when needed. This is done, after the user specifies the minimum idle time, without additional action or attention by the user or an application program.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 2

Automatic DISK POWER Reduction for Portable Computers

Disclosed is hardware and software which reduce the power consumed by a fixed disk subsystem, by turning power to the disk off after an idle period and restoring power when needed. This is done, after the user specifies the minimum idle time, without additional action or attention by the user or an application program.

A part of this design consists of electrical circuits which permit the removal of power from the disk subsystem and isolate the computer bus from the non- powered disk subsystem when power is off. Power switching can be accomplished by means of a relay, transistor or other suitable device. Bus circuit isolation is done with standard digital drivers and receivers. Additional circuitry is used to control these switches, and consists of flip-flops controlled by the computer system. These flip-flops are the POWER ENABLE, the BUS ENABLE and the DISK RESET devices. Each flip-flop may be set or reset by the computer.

The other part of this design is the addition of power control firmware to the computer read-only memory (ROM). This firmware has three functions. The first function comes into play when the computer is powered on, and consists of the following steps: 1. Set POWER ENABLE on, powering up the disk drive.

2. Set BUS ENABLE off, isolating the bus.

3. Set DISK RESET on, starting a reset of the disk

subsystem.

4 Delay a sufficient time to allow the disk

subsystem to act upon the reset signal.

5. Set DISK RESET off.

6. Set BUS ENABLE on, for normal operation.

7. Install a program which will be called by

interrupts from a hardware real-time clock, which

will count the time that the disk system has been

idle, and set the idle counter to the specified

time.

The second function of th...