Electrical computers and digital processing systems: support – Computer power control – Power conservation
Reexamination Certificate
1999-04-30
2001-12-04
Thai, Xuan M. (Department: 2181)
Electrical computers and digital processing systems: support
Computer power control
Power conservation
C713S320000, C713S322000
Reexamination Certificate
active
06327664
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to memory cards and their use in computer systems, and more particularly to the use in computer systems of memory cards having signal processing units on board and having at least one and preferably a plurality (i.e. at least two) of addressable banks of memory chips wherein at least a portion of at least one memory bank is individually addressable or activatable.
BACKGROUND ART
Memory cards such as SIMMs and DIMMs have increasingly more memory and more function being added thereto. Particularly, it has been proposed that signal processing elements such as digital signal processors (DSPs) be provided on board the cards to perform various functions independently of the system memory controller. These DSPs can operate on the memory when it is not being accessed by the system memory controller to perform various tasks.
This provides an inexpensive processor specific to each card to enhance the operation of the memory card. Additionally, as the amount of memory and the functions supplied on each card increase the power requirement for the card with large amounts of memory and more functions, this power requirement can be substantially increased. This is especially critical where the system is battery operated and/or the heat dissipation capability is limited. While the system memory controller generally is programmed to reduce the power level of the memory system, this is generally not a completely satisfactory solution since the memory controller operates on all of the memory cards and generally does not reduce the power state of the memory until the period of non-use amounts to a substantial period of time. Also the system memory controller is not normally programmed to operate on individual portions of memory banks. Thus there is a need for a memory card and system for the memory card to operate in a computer to selectively and expeditiously reduce power to individual banks of memory or portions thereof when the banks of memory or portion thereof are not being accessed by either the system memory controller or the DSP.
SUMMARY OF THE INVENTION
According to the present invention an improved memory card and its use in a computer system is provided. The card includes a signal processing element, preferably a DSP and at least one and preferably first and second individually addressable banks of memory chips. The first bank of chips or optionally a portion of the first bank of chips is configured to function principally under the control of the signal processing element and the second bank is configured to function principally under the control of a system memory controller in the computer system, although all the portions of each of the memory banks is addressable by both the signal processing element and the system memory controller. Both banks of memory chips or portion thereof can be placed in at least one higher power state and at least one lower power state by either the system memory controller or the DSP. The activity of each bank of memory and portion thereof is sensed while in the higher power state, and the condition of each of the banks of memory or portion thereof is sensed with respect to any activity during operation of the memory bank of memory at the higher power state. The power state of each bank of memory can be changed by either the signal processing element or the system memory controller responsive to preselected conditions of each bank. Each memory bank or portion thereof is returned to a predetermined known condition when changing from a lower power state to a higher power state. Preferably this condition is that condition, in the case of the memory bank under the control of the system memory controller that it was in following the last access by the system memory controller, and in the case of the memory bank or portion thereof under the control of the DSP, is a given preselected condition. This is especially important when the memory bank assigned to the system controller is placed in another state by the DSP.
REFERENCES:
patent: 5560024 (1996-09-01), Harper et al.
patent: 5638542 (1997-06-01), Nikjou
patent: 5689714 (1997-11-01), Moyer
patent: 5692202 (1997-11-01), Kardach et al.
patent: 5721933 (1998-02-01), Walsh et al.
patent: 5727221 (1998-03-01), Walsh et al.
patent: 5901103 (1999-05-01), Harris, II et al.
Dell Timothy J.
Hazelzet Bruce G.
Kellogg Mark W.
Miller Christopher P.
Hogg William N.
International Business Machines - Corporation
Thai Xuan M.
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