IBM Multiprise 3000, Reference Manual, Page: 77 / 264

Write Trackset – ‘11’ Extended Operation Code: The Write Trackset Operation
prepares the control unit to update the Record Zero data area and format write the
user data records on one or more tracks. The tracks to be written are specified by
the Extended Parameter and the number of tracks to be written is specified by the
Count parameter.
If the file mask does not permit format write operations (bits 0-1 = ‘01’ or ‘10’),
Locate Record Extended is terminated with status that includes unit check
(Command Reject, format 0, message 2, Invalid Command Sequence).
The maximum length of the Extended Parameter is specified in byte 43 of the
Device Characteristics Information (See Appendix A, "Device Characteristics" on
page A-1.).
The Extended Parameter contains a bit map that represents a set of sequentially
addressed tracks within the defined extent. Each bit in the map represents one
track. A ‘1’ bit indicates that the corresponding track is to be formatted. A ‘0’ bit
indicates the track is to be skipped.
The first bit in the bit map must be a ‘1’ and represents the track whose address is
specified in the Seek Address parameter (bytes 4-7). Subsequent bits represent
consecutively addressed tracks in ascending order. If the first bit is not a ‘1’, Locate
Record Extended is terminated with status that includes unit check (Command
Reject, format 0, message 4, Invalid Parameter).
The number of ‘1’ bits in the bit map must be equal to the value in the Count
parameter (byte 3); otherwise Locate Record Extended is terminated with status
that includes unit check (Command Reject, format 0, message 4, Invalid
Parameter).
All tracks in the bit map represented by ‘1’ bits must be within the defined extent;
otherwise Locate Record Extended is terminated with status that includes unit
check (File Protected).
Track access is initiated using the Seek Address parameter and a Sector value of
zero; the Sector Number is not used.
The Locate Record Extended orientation bits (byte 0, bits 0 and 1) have only one
valid setting, count orientation. However, Internal Disk uses home address
orientation while executing Write Trackset. When track access is completed, the
control unit orients to Home Address. Prior format write operations may cause the
track to contain or not contain a Record Zero (R0). In either case, Internal Disk next
checks the search argument to assure that it contains the expected value of the
record ID field in the Record Zero count area. The expected values of the search
argument are:
CCHH value equal to the track that is to be written.
R value set to x‘00’.
Unit check status with the sense data including No Record Found occurs if the
search argument is not as expected.
Locate Record Extended must be followed by the number of Write Full Track
commands specified in the Count parameter (byte 3). If any other command
sequence is detected within the Locate Record domain, the non-conforming
command will be rejected with status that includes Unit Check (Command Reject,
Chapter 4. Command Descriptions
4-39