Resilient bus system
First Claim
1. A system including a plurality of units coupled in common to a system bus for transferring requests between said plurality of units during different allocated bus cycles of operation, each request being transferred during a number of said allocated bus cycles of operation, said system further including:
- means included in at least one of said plurality of units for generating requests on said bus, each request containing a number of different parts, said parts each containing a number of integrity bits for verifying when said request is validly received by another unit of said plurality of units designated by said request during each of said number of allocated bus cycles of operation and at least one of said parts being coded to specify an operation to be performed by said another unit;
checking means included in said another unit, said checking means being coupled to said bus for verifying during each allocated bus cycle of operation that all of said number of different parts of said each request received from said bus by said checking means of said another unit are valid;
response means included in said another unit, said response means being coupled to said checking means and to said bus, said response means being inhibited by said checking means from generating any response on said bus to said one unit signalling acceptance of said request when said checking means verifies that less than all of said parts of said received request received during said each allocated bus cycle of operation are valid; and
,means for accepting said request, said means for accepting being coupled to said bus and to said response means, said means for accepting being enabled to accept said request from said bus during each of said allocated bus cycles of operation upon said response means signalling said acceptance of said request and said means for accepting, rejecting said request applied to said bus during each of said allocated bus cycles of operation when said response means is inhibited from generating any response on said bus thereby ensuring that said another unit does not attempt to perform any operation specified by an invalid request.
1 Assignment
0 Petitions
Accused Products
Abstract
A data processing system includes a plurality of units which are coupled to transfer requests including data, command and integrity signals between units over a system bus during allocated bus transfer cycles. Each unit includes response apparatus for acknowledging requests received from other units. Each of a number of units further includes retry apparatus and checking apparatus for verifying that all of the parts of a request received from such unit over the bus are valid. When less than all of the parts of the request are detected as valid, the receiving unit does not accept the request and inhibits its response apparatus from generating a response. This prevents damage to system integrity and permits each unit with retry apparatus to retry the request during a subsequent bus transfer cycle.
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Citations
20 Claims
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1. A system including a plurality of units coupled in common to a system bus for transferring requests between said plurality of units during different allocated bus cycles of operation, each request being transferred during a number of said allocated bus cycles of operation, said system further including:
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means included in at least one of said plurality of units for generating requests on said bus, each request containing a number of different parts, said parts each containing a number of integrity bits for verifying when said request is validly received by another unit of said plurality of units designated by said request during each of said number of allocated bus cycles of operation and at least one of said parts being coded to specify an operation to be performed by said another unit; checking means included in said another unit, said checking means being coupled to said bus for verifying during each allocated bus cycle of operation that all of said number of different parts of said each request received from said bus by said checking means of said another unit are valid; response means included in said another unit, said response means being coupled to said checking means and to said bus, said response means being inhibited by said checking means from generating any response on said bus to said one unit signalling acceptance of said request when said checking means verifies that less than all of said parts of said received request received during said each allocated bus cycle of operation are valid; and
,means for accepting said request, said means for accepting being coupled to said bus and to said response means, said means for accepting being enabled to accept said request from said bus during each of said allocated bus cycles of operation upon said response means signalling said acceptance of said request and said means for accepting, rejecting said request applied to said bus during each of said allocated bus cycles of operation when said response means is inhibited from generating any response on said bus thereby ensuring that said another unit does not attempt to perform any operation specified by an invalid request. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system including a plurality of units of new and old designs coupled in common to a system bus for transferring requests between designated ones of said plurality of units during different asynchronously generated bus cycles of operation, said system further including:
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first means included in at least a first unit of said plurality of units of said new design for generating requests on said bus, each request containing a number of different parts, each of said parts containing at least one integrity bit for verifying that said request is validly received by a second cycle of operation; said system bus including a new parity line coupled only to each of said units of new design; second means included in said first unit of said new design for applying a predetermined signal to said new parity line which identifies to a second one of said plurality of units said new design receiving said request that said request includes all integrity bits required for verifying that all of said number of parts of said request are valid; checking means included in each of said plurality of units of said new design, said checking means of each of said units of new design being coupled to said new parity line and operative in response to said predetermined signal to verify that all of said number of different parts of said request designating said unit received from said bus by said unit are valid; and
,response means included in each of said plurality of units of said new design and in each of said units of said old design, said response means of each of said units of said new design being coupled to said checking means associated therewith and to said bus, said response means of each of said units of said new design when designated by said request being inhibited by said checking means from generating any response to said request on said bus to said first unit when less than all of said parts of said received request are valid and said response means of each of said units of said old designs when designated by said request generating a response on said bus to said first unit subsequent to receiving said request in the same manner as said response would have been generated in a system which included only units of said old design. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of operating a bus system in a resilient manner when transferring requests during different allocated bus cycles of operation between a plurality of data handling units coupled in common to said bus system, each request being transferred during a number of said allocated bus cycles of operation, said method comprising the steps of:
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(a) generating requests on said bus system by means included in at least one of said data handling units, said each request containing a number of different parts, said parts each containing a number of integrity bits for verifying when said request is validly received by another unit designated by said request of said plurality of units during each of said number of allocated bus cycles of operation and at least one of said parts being coded to specify an operation to be performed by said another unit; (b) checking by checking means included in at least another one of said data handling units, to verify that all of said number of different parts of said each request received by said another data handling unit from said bus during each allocated bus cycle of operation are valid; (c) generating a response on said bus by response means included in said another one of said data handling units when enabled by said checking means; (d) enabling said response means for generating a response on said bus only when all of said parts of said request received during said each allocated bus cycle of operation are signalled by said checking means as being valid; accepting said request from said bus during each allocated bus cycle of operation when a response is generated signalling the receipt of a valid request; and
,rejecting the request applied to said bus during each allocated bus cycle of operation when no response is generated signalling the receipt of an invalid request thereby ensuring that said another one of said data handling units does not attempt to perform any operation specified by an invalid request. - View Dependent Claims (18, 19, 20)
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Specification