Write Full Track - IBM Multiprise 3000 Reference Manual

Write Full Track

Hex Code Data Address
95 The main storage location of the first
parameter byte.
Description: The Write Full Track command transfers data from the channel and
writes the data on the track.
Write Full Track is valid only in the domain of a Locate Record Extended command
that specified the Write Trackset (11) Extended Operation code.
The first Write Full Track command in the Locate Record domain transfers a track
image from the channel (see Figure 4-1 on page 4-101) verifies the KL and DL of
Record Zero then update writes the eight byte data area of Record Zero, and then
format writes user data records on the track.
The control unit expects to transfer, from the channel, the count, key and data
areas for all records on the track from R0 through the last user record, followed by
a pseudo count field (eight bytes of x'FF'). The minimum CCW byte count is 24,
consisting of an eight byte R0 count field, an eight byte R0 data field, and an eight
byte pseudo count field. The minimum count allows an update write of R0 and the
remainder of the track to be erased. If the control unit does not receive all of the
data expected, execution is terminated with status that includes unit check
(Command Reject, format 0, message 3, CCW byte count less than required).
The Write Full Track command formats a new Record Zero on the track similarly to
a Write Record Zero operation. Accordingly, restrictions on the content of the
information to be placed in the Record Zero are consistent with the restrictions of a
Write Record Zero operation. The first 8 bytes of the record (CCHHRKlDl)
transferred from the channel are the count area: cylinder number (2 bytes), head
number (2 bytes), record number (1 byte), key length (1 byte), and data length (2
bytes).
The area must define a standard R0 count field as follows:
If any of these restrictions are violated, the operation is rejected with unit check.
The sense data contains command reject with format 0, message 4, Invalid
Parameter.
Next the eight byte R0 data field is update written.
Following the R0 are the Count, Key and Data fields for the user records on the
track. Each block of data is processed as follows:
The CCHH specified must be equal to the currently addressed cylinder and
track.
The R value specified must be zero.
The Key Length (Kl) must be zero.
The Data Length (Dl) must be 8.
1. The first eight bytes are examined to determine if they are the pseudo count
field (eight bytes of x'FF'). If there are not eight bytes available from the
Count
Number of bytes to be transferred.
Chapter 4. Command Descriptions
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