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dlps:result_descriptor [2019/02/03 10:47] (current)
scott created
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 +====== Result Descriptor ======
  
 +The I/O result descriptor is generated by the I/O control at the completion of each I/O operation.  It is stored in a fixed location of reserved memory that is dependent upon the I/O channel that is being used (refer to XXX).   The format of the result descriptor is as follows:
 +
 +^  Bit  ^  Function  ^
 +|  1  | This bit is on when an I/O complete has occurred on the I/O channel for the reserved result descriptor.  |
 +|  2  | This bit is on when an exception condition occurred during the I/O operation.  |
 +|  3 - 16  | These bits indicate specific exception conditions, unique to each I/O control  |
 +
 +The privileged instruction, [[instructions:srd|Scan Result Descriptor]] is used by the Master Control Program to test for a result descriptor with bit 1 ON, indicating an I/O complete has taken place on the specific channel.   In addition, a test is made of the status of bit 2 to determine if an exception condition occurred on the initiated I/O operation.  The specific exception conditions are detailed in the descriptions of each [[:iocontrols|I/O control]] or [[:dlps|Data Link Processor]].
dlps/result_descriptor.txt ยท Last modified: 2019/02/03 10:47 by scott
 
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