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3.1 Control/Sense Commands
C141-E167 3 -
25
c. Page descriptor
The "Page descriptor" is configured from a 2-byte page header followed by a parameter field and
each parameter function attribute is classified in a unit called a "Page." The individual "Page
descriptors" in the MODE SELECT and MODE SELECT EXTENDED commands may be
specified independently by the INIT and multiple "Page descriptors" may be specified
continuously in the desired sequence.
• Page code
This field specifies a code (Page No.) that indicates the type of "Page descriptor."
• Page length
This field indicates the length of the parameter field (number of bytes) after byte 2,
excluding the page header, of the "Page descriptor" and is a fixed value for each page code.
The INIT must specify the same value as the page length reported by the IDD in the MODE
SENSE or MODE SENSE EXTENDED command, except in cases it is described in each of
the page descriptor descriptions in this item.
d. MODE SELECT parameters of the IDD
The parameter list configuration and its length that can be transferred to the IDD by the INIT in
the MODE SENSE or MODE SENSE EXTENDED command are as shown below. If a "Page
descriptor" that is not supported by the IDD is specified, the command is terminated with a
CHECK CONDITION status (ILLEGAL REQUEST [=5] / Invalid field in parameter list [=26-
00]), and all the MODE SELECT parameters transferred in the command are disabled.
Parameter B
y
te Len
g
th
Header 4
Block Descriptor 8 or 0
Page Descriptor Page 1: Read/Write Error Recovery Parameter 8 or 12
Page 2 Disconnect/Reconnect Parameter 12 or 16
Page 3: Format Parameter 24
Page 4: Drive Parameter 20 or 24
Page 7: Verify Error Recovery Parameter 12
Page 8: Caching Parameter 12 or 20
Page A: Control Mode Parameter 8 or 12
Page C Notch Parameter 24
Page 1C Information exceptions control parameter 12
Page 21: Additional Error Recovery Parameter 4
Notes:
1. The MODE SELECT parameter is ordinarily different in its configuration depending on the
input/output device and the type of controller. It is also possible that current definitions may
be expanded in accordance with the expansion of the functions of the IDD in the future. In
order to assure independence of software from the individual specifications of input/output
devices, before the INIT issues this command, it should follow the procedure of using the
MODE SENSE and MODE SENSE EXTENDED command to determine the types of
parameters the TARG is actually equipped with and the attributes of those parameters, such
as whether or not they can be changed.