Electrical computers and digital processing systems: support – Computer power control – Power conservation
Reexamination Certificate
1998-09-10
2001-05-29
Follansbee, John A. (Department: 2154)
Electrical computers and digital processing systems: support
Computer power control
Power conservation
Reexamination Certificate
active
06240521
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to information processing systems, and more specifically to power conservation in battery operated computer systems. The invention has a particular applicability to IBM® ThinkPad®) notebook computers. (IBM and ThinkPad are registered trademarks of the International Business Machines Corporation.)
BACKGROUND OF THE INVENTION
Various low-powered operating modes for extending battery life are known in notebook computers and hand-held devices. A sleep mode (also known as a “suspend” mode) permits a user to press a button which places the computer in a very low power configuration in which program execution is suspended. When the button is depressed a second time, the computer resumes execution from the point at which the button was depressed the first time. In some power-conserving operating modes, a computer will enter a sleep mode automatically if there has been no user activity within a defined interval.
In other efforts to extend battery life, computer circuits have been developed which provide reasonable computational speed when operated at reduced voltages. It is fair to say, however that no existing notebook computer offers the combined advantages of low power and high speed.
What is needed is a notebook computer that can operate at extremely low power levels when battery life is at a premium—such as during a long distance flight—and can operate at high speed when computational power is required. The current solution to this problem is to use two computers—a low-powered notebook for an extended flight, and a high-powered notebook or desktop computer for heavy number crunching.
SUMMARY OF THE INVENTION
This need, and others that will become apparent, is met by the present invention which in a specific embodiment provides an information processing system having at least two processors sharing a common instruction set and address space. One processor at a time is active and executes program instructions. The active processor is placed into a sleep mode in which a current machine state is saved in the shared address space and instruction execution is suspended. A different processor becomes active and resumes instruction execution using the previously saved current machine state. The sleep mode is used to effectively pass control from one processor to another.
In a specific embodiment, the currently active processor will resume operation after a sleep mode unless the user overrides that default selection. In another specific embodiment, the currently active processor selects which processor will become active following a sleep mode transition.
In another specific embodiment, different processors share a common instruction set but each has additional unique characteristics, and the currently active processor selects a processor having characteristics matching the requirements of a specific phase of a computational process.
In another specific embodiment, a notebook computer has two processors, one being very low-powered for extending battery life, the other being very fast for multimedia presentations and heavy number crunching. A user selects a processor appropriate for the intended use.
Another specific embodiment of the invention defines methods for operating an information processing system having plural processors using a sleep mode transition as described above. One specific method requires that the computational process be expressed in shared instructions and address space only. Another specific method permits the software, via the processor selection latch, to specify which processor will be active during various phases of the software, thereby permitting the software to take advantage of individual characteristics of each processor.
A primary advantage of the system is that a low power processor can be used for some tasks, such as word processing, for prolonging battery life, while a powerful high-speed processor can be invoked for tasks such as spread sheets and multimedia presentations. In the past, these combined features required that more than one computer be used. The present invention permits these features to be available in a single computer system.
Another advantage of the described system is that it permits desirable characteristics of similar though different processors to be successfully combined in a single computer. The differing characteristics typically include speed and power, but also permit processors from different manufacturers and having slightly differing characteristics to be combined in a single desktop or notebook computer. This advantage is one not previously available except by using two computers. The two processors must share a common subset of instructions and an address space.
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Barber Ronald Jason
Selker Edwin Joseph
Benson Walter
Buckley Robert
Follansbee John A.
International Business Machines Corp.
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