11 October 1988 X3T9.2/88-132 rev. 1 TO: John Lohmeyer, Chairman X3T9.2 From: Bob Pentecost, Hewlett Packard Subject: Parameter Pointer for Log Sense Command Problem 1 The Log Sense command currently allows access to most recently updated parameters, but not to a specific parameter. Proposed Solution Change "Number of Recent List Parameters" (bytes 5-6) to "Parameter Pointer." Add "PPC" (Parameter Pointer Control) to byte 1, bit 1 (replaces a reserved bit). Add text: A PPC bit of one specifies that the Parameter Pointer shall be the number of recent list parameters. [The number of recent list parameters remains as currently defined.] A PPC bit of zero specifies that the parameter data shall start with the parameter specified in the Parameter Pointer field. If the Parameter Pointer is larger than the number of list parameters on the page, then the target shall terminate the command with a CHECK CONDITION status. The sense key shall be set to ILLEGAL REQUEST, and the additional sense code shall be set to ILLEGAL FIELD IN COMMAND DESCRIPTOR BLOCK. Problem 2 The Log Page Descriptor (Table 7-59) provides a "Page Length" field but the text describes a "page parameter length field." This needs to be clearly defined as to whether it is the length of the page or the length of the parameters being transferred. Proposed Solution Change bytes 2-3 in Table 7-59 to "Parameter Length" and the text to refer to that designator. [This allows a partial page to be transferred. If the length of the page needs to be known, a counter can be implemented.] Problem 3 There is currently no way to transfer all parameters with the Log Sense command unless the number of parameters is known and specified in Number of Recent List Parameters. Proposed Solution The solution to Problem 1 allows all parameters to be transferred by setting PPC to zero and the Parameter Pointer to zero.