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COMMON COMMAND SET AND DISK OPERATION
A-4
A
The information for each page below is used with each format parameter listed
in the FORMAT PARAMETER PAGE. The FORMAT command performs the
following to a Winchester disk:
Mode sense for FORMAT PARAMETER PAGE 3 current values.
If no illegal request error
Mode sense for page 3 changeable values.
If any of the previous mode sense commands returned a "Illegal Request" error
status, this next step is skipped (mode sense and mode select are optional). If
the previous commands were successful, a mode select command and
parameter list is prepared.
If the attach packet value does not match the mode sense value, and if the
changeable value is not zero (some bits are changeable), try to put the attach
packet value into the field using the changeable mask.
NOTES:
1. If the previous attach command was the "old" ATTACH ($08) or the
"new" ATTACH ($78) and the physical-bytes-per-block is equal to the
logical-bytes-per-block, the logical block address is taken from the
user packet byte offset $08.
If the previous attach command was the "new" ATTACH ($78) and
the logical-bytes-per-block is a multiple of the physical-bytes-per-
block, the logical block address is calculated by multiplying the
starting sector number (byte offset $8) by the logical to physical ratio.
An example would be logical-bytes-per block = $400, physical-bytes-
per-block = $200, and the users starting sector number = $600. The
calculated ratio would be 2, and the new starting sector number
would be 2 * $600 = $C00.
2. If the previous attach command was the "old" ATTACH ($08) or the
"new" ATTACH ($78) and the physical-bytes-per-block is equal to the
logical-bytes-per-block, the number of sectors is taken from the user
packet byte offset $0C.
If the previous attach command was the "new" ATTACH ($78) and
the logical-bytes-per-block is a multiple of the physical-bytes-per-
block, the transfer length is calculated by multiplying the number of
sectors (byte offset $C) by the logical to physical ratio. An example
would be logical-bytes-per block = $400, physical-bytes-per-block =
$200, and the user number of sectors = $30. The calculated ratio
would be 2, and the transfer length would be 2 * $30 = $60.