Fujitsu M2488 manual Chapter Tape Processing, Changing Mode Parameters

M2488 PRODUCT GUIDE TAPE PROCESSING

CHAPTER 7

TAPE PROCESSING

7-1 INTRODUCTION

The following information is located in this chapter:

7-2 CHANGING MODE PARAMETERS

7-3 PERMANENT ERROR HANDLING

7-2 CHANGING MODE PARAMETERS

7-2.1 Initiator Setup

To ensure that the MODE SELECT command performs the desired operations, it is strongly recom- mended that the initiator adhere to the following steps:

1.Issue a MODE SENSE command requesting the target to return all Changeable Values (PC field 01b and Page Code 3Fh in byte two of the MODE SENSE CDB) and preserve the “changeable” values.

2.Issue a MODE SENSE command requesting the target to return all Current Values (PC field 00b and Page Code 3Fh in byte two of the MODE SENSE CDB) and preserve the “current” values.

3.Perform a bitwise AND operation of the “current” values with the one’s complement of the “changeable” values, (this step is important because the target will not accept the command if any non-changeable field is set to a value other than the “current” value).

4.Make further desired changes to bytes which are changeable.

5.Make sure that the PS bit in every mode page is 0 (the MODE SENSE command will report a 1 in the PS bit, but a MODE SELECT command will fail if mode pages are sent with the PS bit set to 1).

6.Issue a MODE SELECT command, sending these parameters:

A PF bit of 0 or 1 both indicate that the MODE SELECT parameters are structured as pages of related parameters as defined by the ANSI standard.

A Save Pages (SP) bit of zero indicates the target shall perform the specified MODE SELECT operation, and shall not save any pages in non-volatile memory. A SP bit of one indicates that the target shall perform the specified MODE SELECT operation, and shall save to a non-vol- atile location all the savable pages including any sent during the DATA OUT phase. Pages which are saved are identified by the Parameter Savable(PS) bit that is returned in the page header by the MODE SENSE command. If the PS bit is set in the MODE SENSE data the page shall be savable by issuing a MODE SELECT command with the SP bit set. Once a MODE SELECT command with an SP bit of one is completed successfully, the parameters set during that command become the “saved parameters”. The “saved parameters” become the active or “current parameters” until another MODE SELECT command is completed. If the new MODE SELECT command has an SP bit of 0, the new parameters are kept as the “cur- rent parameters” (the “saved parameters” remain unchanged) and remain in effect until any of the following occurs:

a)a new MODE SELECT command is successfully performed,

b)a RESET CONDITION is detected,

c)a power on cycle is performed, or

April 1997 CG00000-011503 REV. A 7-1