User`s manual

IOT - I/O Configure Disk Controller
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Note that during a boot, the configuration sector is normally read
from the disk, and the device descriptor table for the LUN used is
modified accordingly. If you wish to read/write using IOP from a
disk that has been booted, IOT will not be required, unless the
system is reset.
A device probe with entry into the device descriptor table is done
whenever a specified device is accessed via IOT.
The device probe mechanism utilizes the SCSI commands Inquiry
and Mode Sense. If the specified controller is non-SCSI, the probe
simply returns the status device present and unknown. The
device probe makes an entry into the device descriptor table with
the pertinent data. After an entry has been made, the next time a
probe is done it simply returns with the status device present
(pointer to the device descriptor).
Note that reconfiguration is only necessary when you wish to read
or write a disk which is different than the default set by the IOP
command. Reconfiguration is normally done automatically by the
PBOOT command when booting from a disk which is different
from the default.
When invoked without options, the IOT command enters an
interactive subcommand mode where the descriptor table values
currently in effect are displayed one-at-a-time. You may change the
displayed value by typing a new value, followed by the Return key.
To leave the field unaltered, press the Return key without typing a
new value.
You may also enter a special character, either at the prompt or after
typing new data, for
scrolling through the fields. The special
characters are: