Integrated circuit I/O using a high performance bus interface
First Claim
1. A computer system comprising:
- a bus;
a semiconductor device coupled to the bus, the semiconductor device comprising an access-time register operative to store a value indicative of a delay time for the semiconductor device to respond to a bus transaction request; and
a bus master coupled to the bus, the bus master transmitting the value and the bus transaction request to the semiconductor device via the bus, wherein the semiconductor device responds to the bus transaction request after the delay time.
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Abstract
The present invention includes a memory subsystem comprising at least two semiconductor devices, including at least one memory device, connected to a bus, where the bus includes a plurality of bus lines for carrying substantially all address, data and control information needed by said memory devices, where the control information includes device-select information and the bus has substantially fewer bus lines than the number of bits in a single address, and the bus carries device-select information without the need for separate device-select lines connected directly to individual devices.
The present invention also includes a protocol for master and slave devices to communicate on the bus and for registers in each device to differentiate each device and allow bus requests to be directed to a single or to all devices. The present invention includes modifications to prior-art devices to allow them to implement the new features of this invention. In a preferred implementation, 8 bus data lines and an AddressValid bus line carry address, data and control information for memory addresses up to 40 bits wide.
213 Citations
22 Claims
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1. A computer system comprising:
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a bus; a semiconductor device coupled to the bus, the semiconductor device comprising an access-time register operative to store a value indicative of a delay time for the semiconductor device to respond to a bus transaction request; and a bus master coupled to the bus, the bus master transmitting the value and the bus transaction request to the semiconductor device via the bus, wherein the semiconductor device responds to the bus transaction request after the delay time. - View Dependent Claims (2)
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3. A semiconductor device receiving a bus transaction request from a bus, the semiconductor device comprising:
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a plurality of conductors coupling the semiconductor device to the bus to receive the bus transaction request; and interface circuitry coupled to the plurality of conductors and including at least one access-time register operative to store a value indicative of a delay time for the semiconductor device, wherein the semiconductor device responds to the bus transaction request after the delay time. - View Dependent Claims (4, 5)
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6. A method for programming a semiconductor device, comprising:
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writing a value to an access-time register of the semiconductor device, the value specifying a delay time for the semiconductor device; receiving a bus transaction request; and responding to the bus transaction request after the delay time. - View Dependent Claims (7)
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8. A memory device, comprising:
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an array of memory cells connected in rows and columns; a plurality of conductors for coupling to an external bus and for carrying address information and data information; and interface circuitry coupled to the plurality of conductors and the array of memory cells for accessing the array of memory cells in response to the address information received from the plurality of conductors, the interface circuitry including an access-time register for storing the data information that defines an access time of the array of memory cells. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A memory device comprising:
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at least one memory section; and a device interface coupling the memory section to a bus, the device interface receiving a bus transaction request from the bus, the device interface comprising at least one register including an access-time register whose contents indicate a delay time after which the memory device responds to the bus transaction request. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A system comprising:
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a bus; a first memory device comprising; a first memory section; a first device interface coupling the first memory section to the bus, the first device interface receiving a first bus transaction request from the bus, the first device interface including a first access-time register whose contents indicate a first delay time after which the first memory device responds to the first bus transaction request; and a second memory device comprising; a second memory section; a second device interface coupling the second memory section to the bus, the second device interface receiving a second bus transaction request from the bus, the second device interface including a second access-time register whose contents indicate a second delay time after which the second memory device responds to the second bus transaction request, wherein the first memory device is capable of transferring information on the bus during the second delay time of the second memory device.
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Specification