Compaq Computer Corporation, Inc.

Compaq Information Technologies Group, L.p.

Campaq Computer Corporation

Kenneth W Stufflebeam

Norman P Brown

Walter G Fry

Paul C Stanley

David M Douglas

Roger P Anderson

Richard Tomaszewski

James D Parzych

Context or other functional settings are protected during a power up reset sequence in a computer system, without the need to save such context or settings in static memory. A signal, representing a change in the context, is delayed beyond a critical period of indeterminacy resulting from a power up sequence. Reliable signals, set before an application of power, negotiate the delay prior to an assertion of a power up reset signal. The context or settings are preserved by bypassing the reset signal. Unreliable signals, set during an application of power, are held by the delay to allow the reset signal to clear or initialize the context or settings. The reset function operates without prior knowledge, for example as saved in static memory, of the state of the context.

Method/apparatus for preserving state of an event during powerup reset sequence based on state of an event signal immediately prior to the reset

A clock control technique allows reducing the power consumption of devices connected to a computer bus. Individual idle devices can be disconnected from the bus clock by a device clock controller and placed in a low-power state without waiting for all devices on the bus to go idle. When individual devices are idle, transactions on the bus are monitored and unclaimed transactions are claimed by the device clock controller, which then forces a retry of the transaction and reconnects the clock to the idle devices. This brings these devices from the low-power state to a full power state, where they are capable of claiming the transaction when it is retried.

Enhanced PCI clock control architecture

A computer which has an ACPI compliant PCI-to-PCI bridge allows additional devices to be inserted, and allows existing devices to be removed or relocated without restarting the computer. A first PCI bus serves as a local bus, allowing a number of devices, including a PCI-to-PCI bridge, to be connected to the processor of a computer system. The first PCI bus also provides power and a clock signal to the PCI-to-PCI bridge and to various other PCI devices located in slots on the bus. The voltage level of the supplied power is controlled by software running on the processor. based on information obtained from the devices during power-up. The PCI-to-PCI bridge allows expansion by coupling a second PCI bus to the first PCI bus, via the PCI-to-PCI bridge. The second PCI bus includes a number of PCI slots, one of which is coupled to the PCI-to-PCI bridge and receives clock and power signals from the PCI-to-PCI bridge. Other devices may be connected to the second PCI bus by inserting the additional devices into slots in the second PCI bus. Additional PCI buses may be connected to the first and second PCI buses by inserting additional PCI-to-PCI bridges into slots in the PCI buses. Only one PCI bridge subsystem need be disabled, i.e. the one to which the new device is to be added or from which a preexisting device is to be removed.

PCI add-in-card capability using PCI-to-PCI bridge power management

A hard drive which prevents data access operations on the hard drive upon power up until the user enters a password. When the computer system is powered up, the hard drive spins up and is tested, responding only to a limited set of commands that do not permit data storage or retrieval operations. The password is located on the hard disk itself to prevent bypassing the hard drive's security using a new computer environment. When the user enters the correct password, the hard drive unlocks and operates as a conventional hard drive. If the user chooses, the hard drive may be unlocked by either of two passwords, one defined by the user and the other by the manufacturer. To obtain access to data areas during a locked state, a wipe data command is provided which overwrites all user data on the drive and unlocks the drive.

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Spring, TX, United States of America

Kenneth W Stufflebeam