Method and apparatus for controlling linear and toggle mode burst access sequences using toggle mode increment logic
First Claim
1. An apparatus for controlling the order in which locations of a memory in a computer system are accessed during a burst access operation, the order being determined by a sequence in which a burst access starting address is incremented, the computer system including toggle increment logic to increment an address in a toggle sequence, the apparatus comprising:
- an input bus to receive burst access requests and corresponding starting addresses from a plurality of devices in the computer system, each starting address indicating a first memory location to be accessed in response to the corresponding burst access request, each of the plurality of devices requiring either a linear or a toggle address increment sequence; and
sequence control logic coupled to the input bus and to be coupled to the toggle increment logic to control the toggle increment logic to increment the starting address in a linear sequence in response to a burst access request from a device requiring a linear address increment sequence, the sequence control logic ignoring accesses to memory locations having addresses indicated by the toggle increment logic which are not included in the linear sequence.
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Accused Products
Abstract
Memory access control logic for controlling sequential and toggle mode burst accesses to a memory in a computer system using toggle mode automatic increment logic. The memory access control logic of the invention controls the sequence in which locations of a memory are accessed during a memory burst access operation wherein the burst access sequence is determined by an order in which a burst access starting address is incremented. Toggle increment logic for incrementing a starting address in a toggle sequence is included in the computer system in which the memory access control logic of the invention is used. An input bus receives a burst access request and a burst access starting address indicating a first memory location to be accessed in response to the burst access request from a device in the computer system. Additional logic determines whether the device requires a linear increment sequence or a toggle increment sequence for the burst access. Control logic controls the toggle increment logic to increment the starting address in a linear sequence in response to determining that the first device requires a linear increment sequence.
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Citations
25 Claims
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1. An apparatus for controlling the order in which locations of a memory in a computer system are accessed during a burst access operation, the order being determined by a sequence in which a burst access starting address is incremented, the computer system including toggle increment logic to increment an address in a toggle sequence, the apparatus comprising:
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an input bus to receive burst access requests and corresponding starting addresses from a plurality of devices in the computer system, each starting address indicating a first memory location to be accessed in response to the corresponding burst access request, each of the plurality of devices requiring either a linear or a toggle address increment sequence; and sequence control logic coupled to the input bus and to be coupled to the toggle increment logic to control the toggle increment logic to increment the starting address in a linear sequence in response to a burst access request from a device requiring a linear address increment sequence, the sequence control logic ignoring accesses to memory locations having addresses indicated by the toggle increment logic which are not included in the linear sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling the order in which locations of a memory in a computer system are accessed during a burst access operation, the order being either a linear order or a toggle order, the order being determined by a sequence in which a burst access starting address is incremented, the computer system including toggle increment logic for incrementing an address in a toggle sequence, the method comprising the steps of:
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receiving a burst access request and a burst access starting address from a first device in the computer system, the starting address indicating a first memory location to be accessed during the burst access operation performed in response to the burst access request; determining whether the first device requires a linear or a toggle address increment sequence for the burst access operation; controlling the toggle increment logic by a sequence control logic to increment the starting address in a linear sequence if the first device is determined to require a linear burst access sequence; and ignoring an access to a particular memory location by the sequence control logic if the toggle increment logic increments the starting address to access the location and the location is not required to be accessed during the burst access operation. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A computer system comprising:
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a processor; a host bus coupled to the processor for communicating information; a memory coupled to the host bus; a peripheral bus coupled to the memory; toggle increment logic coupled to the memory, the host bus and the peripheral bus to increment an address in a toggle increment sequence; and smart increment logic coupled to the memory to control the sequence of a burst access to the memory in response to a burst access request and a burst access starting address received from the host bus or the peripheral bus, the smart increment logic controlling the toggle increment logic to increment the burst access starting address in a linear increment sequence if the burst access request is received from the peripheral bus, the smart increment logic ignoring accesses indicated by addresses from the toggle increment logic which are not included in the linear sequence. - View Dependent Claims (21, 22, 23, 24)
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25. An apparatus for determining the addresses of memory locations to be accessed in response to linear and toggle memory burst access requests specifying a starting address while in a toggle increment mode, the apparatus comprising:
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toggle increment control logic to increment the starting address in one of a plurality of toggle sequences, the particular toggle sequence depending on the starting address, the toggle increment control logic operative in the toggle increment mode; and smart increment control logic coupled to control the toggle increment control logic to increment the starting address in a linear sequence while in the toggle increment mode in response to a linear burst access request, the smart increment control logic using a plurality of toggle increment sequences to produce a linear sequence if the linear and toggle increment sequences corresponding to the starting address are different, the smart increment control logic ignoring addresses indicated by a toggle sequence provided by the toggle increment control logic which are not included in the linear sequence.
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Specification