System for generating error signal to indicate mismatch in commands and preventing processing data associated with the received commands when mismatch command has been determined

An input/output system comprising:

• a plurality of input/output processors, each of said input/output processors capable of receiving data and commands, via a bus, from a plurality of central processing units where each of said input/output processors is responsible for performing like operations on portions of data transmitted thereto over said bus;
• means within each of said input/output processors for generating a control signal indicating a command type received from each corresponding central processing units which is to be executed by said input/output processors;
• means within each of said input/output processors for transmitting said control signal to every other input/output processor;
• means within each of said input/output processors for receiving said transmitted control signals;
• means within each of said input/output processors for comparing said received control signals with said generated control signal;
• means within each of said input/output processors for generating an error signal indicating a mismatch in commands received by each of said input/output processors;
• means responsive to said comparing means for preventing processing of said data when said command mismatch has been determined;
• and
• means for transmitting said error signal to said plurality of central processing units.

A computer system comprising:

• a computer bus;
• a plurality of central processing units, said plurality of central processing units coupled to said computer bus;
• a plurality input/output devices, said plurality of input/output devices coupled to said computer bus such that each one of said input/output devices corresponds to one of said plurality of central processing units and is responsible for processing a portion of data associated with a common command transmitted over said computer bus by said plurality of central processing units and each of said input/output devices further comprising:
• means within said input/output device for generating a control signal indicating a command type which is to be executed by said input/output device;
• means within said input/output device for comparing said generated control signal with received control signals from others of said input/output devices;
• means for generating an error signal indicating a mismatch in commands to be processed by each of said plurality of input/output processors;
• means responsive to said comparing means for preventing processing of said data when said command mismatch has been determined;
• and
• means for issuing a control signal to each of said plurality of central processing units, said control signal being asserted when a mismatched set of commands is received by said plurality of input/output processors.

A method for monitoring command synchronization comprising the steps of:

• transmitting identical command information from a plurality of central processing units to a corresponding plurality of input/output processors;
• receiving said command information within each one of said plurality of input/output processors;
• transmitting a signal from each of a corresponding one of said plurality of input/output processors to each remaining one of said plurality of input/output processors, said transmitted signal indicating a type of command to be performed by the corresponding one of said plurality of input/output processors;
• receiving at each of said input/output processors, the signals transmitted by others of said plurality of input/output processors;
• comparing said transmitted signal to said received signals;
• generating an error signal when said received signals are different from said transmitted signal
• preventing execution of said commands when said received signals are different from said transmitted signal;
• and
• transmitting said error signal to said central processing units.