Microprocessor, semiconductor module and data processing system
First Claim
1. A microprocessor built on a semiconductor chip comprising:
- a central processing unit for executing instructions; and
an external bus interface control circuit which controls an external bus on the basis of execution of instructions by said central processing unit, wherein said external bus interface control circuit is capable of selecting one of a plurality of external device select signals corresponding to an external access address and activating said selected external device select signal, and wherein said microprocessor further comprises a clock switching control circuit for controlling an operation to switch a synchronous clock signal of said external bus interface control circuit in accordance with said external device select signal activated by said external bus interface control circuit.
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Accused Products
Abstract
It is possible to provide a data-processing system wherein a single device such as a microprocessor is capable of selectively making an access to one of high-speed and low-speed devices each operating synchronously with a clock signal peculiar to the device, and clock control can be executed with ease in an operation to switch the external device to be accessed from one to another. Clock signals each having a required frequency are provided individually through separate clock wires to high-speed and low-speed devices to be accessed by a microprocessor. Since control is executed to switch a synchronous clock signal of an external bus interface control circuit embedded in the microprocessor in accordance with an external device or an address area being accessed by the microprocessor, there is exhibited an effect of easy clock control in an operation to switch the external device to be accessed from one to another without the need to switch the clock signal itself which is to be supplied to the external device.
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Citations
14 Claims
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1. A microprocessor built on a semiconductor chip comprising:
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a central processing unit for executing instructions; and
an external bus interface control circuit which controls an external bus on the basis of execution of instructions by said central processing unit, wherein said external bus interface control circuit is capable of selecting one of a plurality of external device select signals corresponding to an external access address and activating said selected external device select signal, and wherein said microprocessor further comprises a clock switching control circuit for controlling an operation to switch a synchronous clock signal of said external bus interface control circuit in accordance with said external device select signal activated by said external bus interface control circuit.
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2. A microprocessor comprising:
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a central processing unit for executing instructions; and
an external bus interface control circuit which controls an external bus on the basis of execution of instructions by said central processing unit, wherein said external bus interface control circuit is capable of activating either a first external device select signal or a second external device select signal corresponding to an external access address, and wherein said microprocessor comprises a clock switching control circuit for controlling an operation to switch a synchronous clock signal of said external bus interface control circuit to a first clock signal in accordance with activation of said first external device select signal or to a second clock signal in accordance with activation of said second external device select signal. - View Dependent Claims (3, 6, 7)
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4. A microprocessor comprising:
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a central processing unit for executing instructions; and
an external bus interface control circuit controlling an external bus on the basis of execution of instructions by said central processing unit, wherein said external bus interface control circuit is capable of activating either a first external device select signal or a second external device select signal corresponding to an external access address, wherein said microprocessor further comprises a clock switching control circuit, wherein said clock switching control circuit is capable of controlling to switch said synchronous clock signal of said external bus interface control circuit to said first clock signal as well as switch a synchronous clock signal of said central processing unit to a third clock signal in response to activation of said first external device select signal, and is capable of controlling to switch said synchronous clock signal of said external bus interface control circuit to said second clock signal as well as switch said synchronous clock signal of said central processing unit to a fourth clock signal in response to activation of said second external device select signal. - View Dependent Claims (5, 14)
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8. A semiconductor module on a module substrate including a plurality of external connection electrodes and a plurality of wiring layers comprising:
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a processor chip; and
a memory chip operating synchronously with a first clock signal, wherein said microprocessor chip includes a clock pulse generator for generating said first clock signal and a second clock signal with a frequency lower than that of said first clock signal and for supplying in parallel said first and second clock signals to outside, wherein said microprocessor chip is capable of making an access to said memory chip synchronously with said first clock signal, and wherein said microprocessor chip is capable of making an external access to outside of said microprocessor chip through one of external connection electrodes synchronously with said second clock signal. - View Dependent Claims (9)
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10. A data-processing system comprising:
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a first clock wire for transferring a first clock signal;
a second clock wire for transferring a second clock signal with a frequency lower than said first clock signal;
a first device operating synchronously with said first clock signal applying through said first clock wire;
a second device operating synchronously with said second clock signal; and
a third device capable of controlling accesses to said first device synchronously with said first clock signal and capable of controlling accesses to said second device synchronously with said second clock signal, wherein said first clock wire, said second clock wire, said first device, said second device and said third device are provided on a mounting board. - View Dependent Claims (11, 12, 13)
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Specification