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Command Specifications
When the "PF (page format)" bit in CDB byte 1 is "1," it indicates that the MODE
SELECT parameters transferred from the INIT by this command are in the "Page
Descriptor" format. The IDD disregards the value specified in this bit and regards the
MODE SELECT parameters transferred from the INIT as being in the "Page
Descriptor" format and executes this command.
The "SP (save pages)" bit in CDB byte 1 specifies whether or not to save the
MODE SELECT parameters specified in this command on the disk. It is possible
for the IDD to save all the MODE SELECT parameters described in the "Page
Descriptor" (except for those on page C), but this bit's specification is valid only
for parameters other than "Format parameters (Page 3)" and "Drive parameters
(Page 4: excluding byte 17)."
If "1" is specified in the "SP" bit, the parameters transferred from the INIT are
saved to the disk when this command is executed, except for "Format parameters
(page 3)" and "Drive parameters (Page 4: excluding byte 17)." When the "SP" bit
is "0," these parameters are not saved to the disk. On the other hand, as for
"Format parameters (Page 3)" and "Drive parameters (Page 4: excluding byte
17)," regardless of the specification of the "SP" bit when this command is
executed, these parameters are always saved to the disk when the FORMAT
UNIT command is executed.
The "Parameter length" field of the CDB specifies the total byte length of the
MODE SELECT parameters transferred from the INIT by this command. If zero
is specified in the "Parameter length" field, this command is terminated normally
without data transfer being executed with the INIT. The MODE SELECT
parameters have specifically defined formats and lengths, as explained by the
descriptions of each page descriptor in this item, and the INIT must always
specify (transfer) those formats and lengths.
If a "Header," "Block Descriptor" or any "Page Descriptor" cannot be transferred
with all the defined length because the total defined length of the MODE
SELECT parameters actually transferred from the INIT do not match the value
specified in the "Parameter List Length" field, or if the total of the MODE
SELECT parameter's defined length transferred from the INIT exceeds the value
specified in the "Parameter list length" field, this command is terminated with a
CHECK CONDITION status (ILLEGAL REQUEST [=5] / Invalid field in CDB
[=24-00]) and all the MODE SELECT parameters transferred in the command are
disabled.
Three types of values exist in the MODE SELECT parameters, "Current," "Save"
and "Default" values. "Current" values are parameters which actually control the
IDD's operation, and the parameters specified by this command are converted to
"Current" values. "Save" values are parameter values specified by this command
which are preserved on the disk. And "Default" values are values which the IDD
uses as "Current" values during the time until reading of "Save" values is
completed after the IDD's power is switched on, or when no "Save" values exist
and no MODE SELECT command is being issued.
4-20
C141-C012
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