Read Count, Key, and Data
Description:
The Read Count, Key, and Data command transfers the entire
count, key, and data areas of a record to the channel. The control unit is oriented
to the next count area and sends the count, key, and data areas of that record.
Chaining and Restrictions:
Unit check status with the sense data containing
command reject with format 0, message 2 occurs if this command is:
Not preceded in the command chain by a Seek, Seek Cylinder, Locate Record,
Locate Record Extended, or a Read IPL command.
In a Locate Record or Locate Record Extended domain that specifies other
than a Read (16) or Read Data (06) operation or a Locate Record Extended
domain with a Read Any (0A) operation.
If end-of-track is detected before a count area is found when in a Locate Record or
Locate Record Extended domain, the operation continues according to the
multitrack bit (bit 0) in the CCW:
If the multitrack bit is ‘0’, the control unit is oriented to the first user data record
count field on the same track. It sends the count, key, and data areas of the
record to the channel. If the track does not have a user data record, the
command is terminated with unit check status. The sense data includes No
Record Found.
If the multitrack bit is ‘1’, the control unit advances to the next track. It sends
the count, key, and data areas of the first user data record to the channel.
(See “Operations in the Domain of a Locate Record or Locate Record
Extended” on page 4-2.) If the track does not have a user data record, the
command is terminated with unit check status. The sense data includes No
Record Found.
If end-of-track is detected before a count area is found when not in a Locate
Record or Locate Record Extended domain, the operation continues according to
the multitrack bit (bit 0) in the CCW:
If the multitrack bit is ‘0’, the control unit is oriented to the count field of the first
user data record on the same track. It sends the count, key, and data areas of
the record to the channel. If the track does not have a user data record, the
command is terminated with unit check status. The sense data includes No
Record Found.
If the multitrack bit is ‘1’, the control unit advances to the next track and
searches until either a user data record is found, or the operation is terminated
with an end-of-cylinder exception. (See “Operations Outside the Domain of a
Locate Record or Locate Record Extended” on page 4-3.)
If the key length field in the count area contains zero, no key area transfer occurs.
If the data length field in the count area contains zero, the control unit does not
send any data area. The command is terminated with channel end, device end,
and unit exception status.
Hex Code
Data Address
Count
1E
Multitrack
9E
The main storage location for the
first byte of the count data.
The number of count,
key and data bytes to be
read.
4-64
Internal Disk Subsystem Reference Guide
Summary of Contents for Multiprise 3000
Page 2: ......
Page 3: ...S 390 IBM Internal Disk Subsystem Reference Guide SA22 1025 00 ...
Page 32: ...2 12 Internal Disk Subsystem Reference Guide ...
Page 38: ...3 6 Internal Disk Subsystem Reference Guide ...
Page 182: ...4 144 Internal Disk Subsystem Reference Guide ...
Page 198: ...5 16 Internal Disk Subsystem Reference Guide ...
Page 214: ...6 16 Internal Disk Subsystem Reference Guide ...
Page 234: ...A 10 Internal Disk Subsystem Reference Guide ...
Page 238: ...B 4 Internal Disk Subsystem Reference Guide ...
Page 243: ...4 lease the Code or any copy of it Appendix C Warranties C 5 ...
Page 244: ...C 6 Internal Disk Subsystem Reference Guide ...
Page 248: ...D 4 Internal Disk Subsystem Reference Guide ...
Page 254: ...X 6 Internal Disk Subsystem Reference Guide ...
Page 263: ......