Method and related apparatus for reducing chipset power consumption

1. Field of the Invention

The present invention relates to a method and related apparatus for reducing power consumption, and more particularly, to a method and related apparatus for reducing chipset power consumption while accessing memory modules.

2. Description of the Prior Art

Computer systems are indispensable to the information society. With the computer system, it is convenient for users to calculate, access, and manage a large amount of information, data, and video at high speed. Therefore, information technology manufacturers have been devoted to improving the performance of computer systems to manage data more securely and speedily. However, while the performance of computer systems is improved, how to reduce power consumption becomes an important issue.

Generally, a typical computer system comprises a central processing unit (CPU), a chipset, a memory device, and other peripheral circuits. The CPU can process information and data to control the operation of the computer system. The memory device, such as a dynamic random-access memory (DRAM), can temporarily store programs, and data required by the CPU. The chipset can manage the communication between the CPU (or other peripheral circuits) and the memory device.

Data is stored in the memory device and has a corresponding address that allows random access. In the computer system, the memory device includes several memory modules. Each memory module has a plurality of address pins, each address pin being used for receiving a one-bit address. The chipset includes a plurality of driving units respectively connected to the address pins of each memory module, each driving receiving power and outputting a one-bit address to a corresponding address pin. When the chipset accesses data of a certain address in the memory device, the chipset will control the driving units respectively to output a one-bit address to the corresponding address pins. Then the memory module gathers all one-bit addresses to obtain a complete address, such as a row address (RAS) or a column address (CAS). According to the assigned address, the chipset can access the required data.

In the prior art, memory modules are independent circuits and combined into a memory device, which is electrically connected to the computer system by insertion into a slot. Depending on the user's budget and requirement, the user can install the required memory capacity. As known in the art, a larger memory capacity requires more bits to assign addresses. Generally, driving units of the chipset are more than address pins of the memory device so as to support different memory capacities or larger memory capacities. For instance, most chipsets can support a 4 GB memory capacity. However, most memory device configurations have a memory capacity smaller than 4 GB and thereby require fewer address bits.

Current chipsets can support the configuration for 2-bit bank addresses and 14-bit RAS/CAS addresses, and therefore the typical chipset includes 16 driving units. Actually, it is only necessary to have 2-bit bank addresses and 12-bit RAS/CAS addresses to assign an address in a 64 MB memory module. However, in the prior art, no matter whether the configuration of the memory module is smaller than the memory capacity supported by the chipset, each driving unit of the chipset still consumes power. Thus, when the prior art computer system accesses the memory device, some address pins of the memory module are not used, but the corresponding driving units still consume power increasing overall power consumption.

It is therefore a primary objective of the claimed invention to provide a method for reducing chipset power consumption while accessing a memory module to solve the above-mentioned problem.

The claimed invention provides a method for reducing computer system power consumption. The computer system includes a memory module having a plurality of address pins, and a chipset having a plurality of driving units for driving the address pins. The method includes obtaining number of required address pins by detecting a configuration of the memory module, and when the number of required address pins is smaller than the number of driving units of the chipset, the chipset controlling at least one driving unit to stop driving so that the number of driving units driven by the chipset is equal to the number of required address pins.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

FIG. 1 is a diagram of a computer system according to the present invention.

FIG. 2 is a flowchart of the operation of the chipset of FIG. 1 .

FIG. 3 is a diagram of another embodiment of a computer system based on the present invention.

FIG. 4 is a flowchart of the operation of the chipset of FIG. 3 .

FIG. 5 is a diagram of the operation of each driving unit when the computer system of FIG. 3 is working.

Please refer to FIG. 1 , which is a diagram of a computer system 10 according to the present invention. The computer system comprises a central processing unit (CPU) 12 , a peripheral circuit 14 , a basic input/output system (BIOS) 16 , a chipset 20 , and a memory module 30 . The CPU 12 processes information and data to control the operation of the computer system 10 . The memory module 30 temporarily stores programs and data required by the CPU 12 . The peripheral circuit 14 can be a hard disc, an optical disc drive or inserted cards, such as a graphic card, a network interface card, a sound card, etc. When booting the computer system, the BIOS 16 not only stores settings and program codes for the basic inspection, but also detects the configuration of the memory module 30 to generate corresponding configuration information. The chipset 20 manages the communications among the CPU 12 , the memory module 30 , the peripheral circuit 14 , and the BIOS 16 .

In order to implement the present invention, the chipset 20 includes an access circuit 21 , an address module 22 , a plurality of driving units 23 (this embodiment has 16 driving units 23 ), a control module 24 , and a buffer module 26 . The access circuit 21 receives the request from the CPU 12 (or the peripheral circuit 14 ) to write data into and read data from a specific address of the memory module 30 . Each driving unit 23 includes one or more output buffers 27 for outputting a sub-address, and one or more input amplifiers 28 (such as a driving amplifier) for receiving signals input into the driving unit 23 . Each driving unit 23 corresponds to a pin, as marked as BA 0 , BA 1 , and MA 0 to MA 13 in FIG. 1 , connected to an address pin 32 of the memory module 30 . When the access circuit 21 writes data in a determined address of the memory module 30 , the address module 22 controls each driving unit 23 based on the determined address accordingly, such that each driving unit 23 outputs one-bit (a sub-address) of the determined address. The control module 24 controls the output buffers 27 or the input amplifiers 28 of the driving units 23 to output or receive signals. In addition, the buffer module 26 temporarily stores the configuration of the memory module 30 detected by the BIOS 16 when booting the computer system 10 . When the chipset 20 operates, the control module 24 determines which driving units 23 are required by the memory module 30 based on information of the buffer module 26 so as to disable (i.e. turn off) unused driving units 23 . Since disabled driving units 23 will stop draining power and stop driving corresponding pins, power consumption can be reduced.

Please refer to FIG. 2 , which is a flowchart of the operation of the chipset 20 . The steps are as follows.

Step S 201 : When the computer system 10 is booted, the BIOS 16 detects the configuration of the memory module 30 to determine how many bits are required to assign an address so that number X of required address pins is determined.

Step S 202 : The number X is stored in the buffer module 26 and is compared to the number of the driving units 23 of the chipset 20 .

Step S 203 : Determine whether the number X is smaller than the number of the driving units 23 of the chipset 20 . If smaller than the number of the driving units 23 , step S 204 is performed.

Step S 204 : When the number X is smaller than the number of the driving units 23 , the control module 24 determines which driving units 23 are unused based on the information of the buffer module 26 , and disables such unused driving units 23 , such that the number of the driving units driven by the chipset 20 is equal to the number X of required address pins to reduce power consumption. If the number X is not smaller than the number of the driving units 23 , the control module 24 does not disable any driving units 23 .

For instance, if the memory capacity of the memory module 30 has 256 MB, which requires 2-bit bank addresses and 13-bit RAS/CAS addresses (13-bitRAS addresses and 10-bit CAS addresses) for addressing, the control module 24 can disable the driving unit 23 corresponding to the pin MA 13 . Pins BA 0 , BA 1 and MA 0 to MA 12 are used to support the configuration of the memory module 30 . Similarly, if the memory capacity of the memory module 30 has 128 MB, which requires 1-bit bank addresses and 13-bit RAS/CAS addresses (13-bit RAS addresses and 10-bit CAS addresses) for addressing, the control module 24 disables the driving units 23 corresponding to pins BA 1 and MA 13 . Fourteen driving units 23 corresponding to pins BA 0 , and MA 0 to MA 12 are used to access the memory module 30 .

Please refer to FIG. 3 , which is a diagram of another embodiment of a computer system 50 based on the present invention. Devices or elements of the computer system 50 in FIG. 3 that have the same functions as those of the computer system 10 in FIG. 1 have the same reference numerals, and repeated details are omitted. In FIG. 3 , the computer system 50 comprises two memory modules 60 and 70 using the same bus line connected to the chipset 40 . In other words, the same driving unit 23 is connected to address pins 62 and 72 of the memory modules 60 and 70 . Another difference from the embodiment of FIG. 1 is that the chipset 40 of FIG. 3 further includes a comparison module 45 . The memory modules 60 and 70 use the same bus line in the computer system 50 , but the configurations of the two memory modules 60 and 70 might not be the same. The comparison module 45 is used to determine which memory module requires more bits to assign addresses and disables (i.e. turns off) driving units 23 accordingly. Briefly, the comparison module 45 is capable of determining the configurations of the memory modules 60 and 70 so as to disable driving units 23 accordingly.

Please refer to FIG. 4 , which is a flowchart of the operation of the chipset 40 . The steps are as follows.

Step S 401 : When the computer system 50 is booted, the BIOS 16 detects the configurations of the memory modules 60 and 70 to determine how many bits are required to assign an address so that a first number X 1 and a second number X 2 of address pins respectively required by the memory modules 60 and 70 are determined. The first address-pin number X 1 comprises numbers of pins for addressing first bank address and first RAS/CAS address, and the second address-pin number X 2 comprises numbers of pins for addressing second bank address and second RAS/CAS address.

Step S 402 : The numbers X 1 and X 2 are stored in the buffer module 26 . The control module 45 derives the numbers of first bank-address pins and second bank-address pins from the numbers of X 1 and X 2 , and sets the maximum of the first bank-address number and the second bank-address number to a bank-address-pin maximum. Also, a RAS/CAS-address-pin maximum is derived from the maximum of the first and the second RAS/CAS-address-pin numbers. The control module 45 determines a required address-pin maximum according to the RAS/CAS-address-pin maximum and the bank-address-pin maximum.

Step S 403 : The required address-pin maximum is compared with the number of driving units 23 of the chipset 20 . When the required address-pin maximum is smaller than the number of the driving units 23 , step S 404 is performed.

Step S 404 : When the required address-pin maximum is smaller than the number of the driving units 23 , the control module 24 determines which driving units 23 are unused based on the information of the buffer module 26 , and disables such unused driving units 23 , such that the number of the driving units driven by the control module 45 is equal to the required address-pin maximum to reduce power consumption. If the required address-pin maximum is not smaller than the number of the driving units 23 , the control module 24 does not disable any driving units 23 .

Please refer to FIG. 5 , which is a diagram of the operation of each driving unit when the computer system 50 of FIG. 3 is working. Suppose that the chipset 40 supports 2-bit bank addresses (BA 0 and BA 1 ) and 14-bit RAS/CAS addresses (MA 0 ˜MA 13 ), each bank and RAS/CAS address corresponding to a driving unit 23 . Therefore, the chipset includes 16 driving units 23 , and corresponding memory modules 60 and 70 respectively include 16 address pins 62 and 72 for receiving sub-addresses from the chipset 40 . Suppose that the memory capacity of the memory module 60 is 64 MB, which requires 2-bit bank addresses, 12-bit RAS addresses, and 9-bit CAS addresses. Therefore, assigning address requires BA 0 , BA 1 and MA 0 to MA 11 . Generally, bits of RAS address are more than bits of CAS address, and an RAS address is transmitted before a corresponding CAS address is transmitted. The memory capacity of the memory module 70 is 128 MB, which requires 1-bit bank addresses, 13-bit RAS addresses, and 10-bit CAS addresses, requiring BA 0 , BA 1 and MA 0 to MA 12 to assign addresses. Since the memory modules 60 and 70 use the same bus line, the memory module 70 only needs BA 0 while the memory module 60 still requires both BA 0 and BA 1 . Therefore, the control module 24 determines that the bank-address-pin maximum is 2 and that the RAS/CAS-address-pin maximum is 13 according to the configurations of the memory modules 60 and 70 . To access the memory modules 60 and 70 , BA 0 , BA 1 and MA 0 to MA 12 are used. The control module 24 will disable the driving unit 23 corresponding to pin MA 13 . In FIG. 5 , the dotted line represents unused address pins 62 and 72 or address pins corresponding to unused driving units 23 . For instance, MA 13 of the memory module 60 , BA 1 and MA 13 of the memory module 70 , and MA 13 of the chipset 40 are unused.

Additionally, each module of the presented invention can be implemented by hardware or firmware codes. For instance, the comparison module 45 and the control module 24 can be logic circuits. In summary, the BIOS 16 automatically detects the configurations of the memory modules 60 and 70 when the computer system 50 is booted. The comparison module 45 of the chipset 40 determines which address pins 62 and 72 are unused according to the detecting result. Then the control module 24 disables such unused driving units 23 . When the computer system 50 accesses the memory module 60 or 70 , the disabled driving units 23 do not receive/consume power. The present invention can disable unused driving units 23 properly when accessing data so as to reduce power consumption. Therefore, when accessed data is larger, power consumption is reduced by disabling unused driving units 23 .

The present invention detects configurations of each memory module by the BIOS when booting the computer system, and determines how many address pins are unused accordingly. Then the chipset disables corresponding driving units to reduce power consumption. For instance, suppose that the chipset can support 2-bit bank addresses and 14-bit RAS/CAS addresses, and therefore includes 16 driving units. The memory device includes two memory modules. One has 64 MB and requires 2-bit bank addresses and 12-bit RAS/CAS addresses to assign addresses, and the other has 256 MB and requires 2-bit bank addresses and 13-bit RAS/CAS addresses to assign addresses. According to the configurations of the memory modules, the chipset only has to drive 15 driving units to output 2-bit bank addresses and 13-bit RAS/CAS addresses so as to access the two memory modules. As mentioned above, the present invention utilizes the BIOS to detect the configurations of memory modules, and then determines which address pins are unused accordingly. The control module disables driving units corresponding to unused address pins so as to reduce power consumption.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.