Multiprocessor interrupt level change synchronization apparatus

Claim 1

A data processing system comprising: a plurality of interrupting units and a plurality of processing units coupled in common to a system bus for asynchronously transferring interrupt requests between said plurality of units and each of said plurality of processing units during different bus cycles of operation, each of said plurality of processing units including: command generating means coupled to said bus for applying commands to said bus during bus cycles of operation granted to said processing unit; interrupt processing apparatus coupled to said bus for receiving said interrupt requests including interrupt signals specifying any one of a number of interrupt levels; and response means coupled to said interrupt processing apparatus, said response means for generating signals on said bus in response to requests from said units; said response means including decode means coupled to said bus, said decode means being operative in response to a command from any one of said processing units applied to said bus during one of said bus cycles of operation specifying a change in interrupt level to generate an output signal; and, said interrupt processing apparatus including: means for storing a current interrupt level, said means for storing being coupled to said bus and including comparison means for comparing said current interrupt level with said interrupt level signals from an interrupting unit; and said means for storing being conditioned by said output signal to load said signals corresponding to said new interrupt level from said bus included as part of said level change command into said means for storing resulting in a change of the processing unit's interrupt level without interference from other units coupled to said system bus.

Claim 3

The system of claim l wherein each of said units include means for signalling the granting of a bus cycle on a priority basis as defined by the position of said each unit on said system bus.

Claim 4

The system of claim l wherein said decode means includes channel number decoder means coupled to said system bus for generating a signal upon detecting that a channel number assigned to said processing unit has been applied to said bus by any one of said processing units and wherein said command includes an address portion coded to include said channel number assigned to said each processing unit, said channel number decoder means in response to said command causing said output signal to be applied to said interrupt processing apparatus for producing said change in interrupt level.

Claim 7

The system of claim l wherein said command includes a command portion coded to specify said change in said interrupt level, each of said interrupting units in response to said command being notified to resume normal operation enabling the transfer of further interrupt requests during subsequent bus cycles of operation.

Claim 14

The system of claim ll wherein each of said units include means for signalling the granting of a bus cycle on a priority basis as defined by the position of said each unit on said system bus.

Claim 15

The system of claim ll wherein said decode means includes channel number decoder means coupled to said system bus for generating a signal upon detecting that a channel number assigned to said unit has been applied to said bus by any one of said units and wherein said command includes an address portion coded to include said channel number assigned to said each unit, said channel number decoder means in response to said command causing said output signal to be applied to said interrupt processing apparatus for producing said change in interrupt level.

Claim 16

The system of claim l3 wherein any one of said units corresponds to said each unit and said channel number corresponds to the unit's own channel number.

Claim 17

The system of claim l3 wherein any one of said units corresponds to a unit other than said each unit.

Claim 18

The system of claim ll wherein said command includes a command portion coded to specify said change in said status level, each of said interrupting units in response to said command being notified to resume normal operation enabling the transfer of further requests during subsequent bus cycles of operation.

Claim 19

The system of claim l6 wherein said level processing means further includes indicator circuit means coupled to said bus and to said means for storing, said indicator circuit means being conditioned by said output signal to switch state specified by said command, said indicator circuit means when in a first state inhibiting said level processing means from accepting requests and said indicator circuit means when in a second state enabling said level processing means to accept requests.

Claim 20

The system of claim l7 wherein said command includes an address portion coded to specify any change in the status of said indicator circuit means.

Claim 21

The system of claim l7 wherein said level processing means further includes register means coupled between said system bus and said means for storing, said register means being enabled during said one of said bus cycles of operation to store signals corresponding to said current status level for application to said means for storing.

Claim 22

A method of changing the operational status of any one of a plurality of units coupled in common to a system bus for asynchronously transferring requests between said plurality of units during different asynchronously generated bus cycles of operation, different ones of said plurality of units each including command generating means coupled to said bus for applying commands to said bus, operating level processing means coupled to said bus for receiving said requests including signals specifying any one of a number of status levels, said operating level means including means for storing a current status and comparison means for comparing said current status with status level signals from an interrupting unit and response means coupled to said level processing means for generating signals on said bus in response to requests from said units, said method including the steps of: (a) requesting a bus cycle of operation; (b) generating by said command generating means, a command specifying a change in operational status of one of said plurality of units, said command including at least first and second portions, said first portion being coded to specify the change in status and said second portion being coded to specify the new operational status; (c) transferring said command to said bus during a bus cycle of operation granted in response to step a; (d) including decode means in said response means for generating an output signal indicating a status change in response to said command portion of said command addressed to said unit; (e) conditioning said means for storing in response to said output signal to switch the operational status of said unit to said new operational status specified by said second portion of said command without interference from any other unit coupled to said system bus; and (f) during the same bus cycle of operation, notifying the remaining units of that a change in status had occurred enabling resumption of normal operation.

Claim 23

A method of changing the operational status of any one of a plurality of units coupled in common to a system bus for asynchronously transferring requests between said plurality of units during different asynchronously generated bus cycles of operation, different ones of said plurality of units each including command generating means coupled to said bus for applying commands to said bus, operating level processing means coupled to said bus for receiving said requests including signals specifying any one of a number of status levels, said operating level means including means for storing a current status and comparison means for comparing said current status with status level signals from an interrupting unit and response means coupled to said level processing means for generating signals on said bus in response to requests from said units, said method including the steps of: (a) requesting a bus cycle of operation; (b) generating by said command generating means, a command specifying a change in operational status of one of said plurality of units, said command including at least first and second portions, said first portion being coded to specify the change in status and said second portion being coded to specify the new operational status; (c) transferring said command to said bus during a bus cycle of operation granted in response to step a; (d) including decode means in said response means for generating an output signal indicating a status change in response to said command portion of said command addressed to said unit; (e) conditioning said means for storing in response to said output signal to switch the operational status of said unit to said new operational status specified by said second portion of said command without interference from any other unit coupled to said system bus; and (f) during the same bus cycle of operation, notifying the remaining units of that a change in status had occurred enabling resumption of normal operation.