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READ COMMANDS
Code
Command
Single
Multi-
Function
Data Read
Track
Track
'
First data area after
address marker or the data
Read Data
06
86
Transfer data area of a record from drive to main
area of the record that was
storage.
chained from the count
or key area of the same
record.
First key and data areas
after address marker or
Read Key Data
OE
SE
Transfer key and data areas of a record from drive to
the key and data areas
(see Note 1)
main storage.
that were command-
chained from the count
area of the same record.
Read Count
1E
9E
Transfer count, key,
an~
data areas of a record from
Next record or first record
Key Data
drive to main storage.
after RO.
Read Record
16
96
Transfer RO (count, key and data) from the drive to
RO
Zero (RO)
main storage.
(see Note 2)
Read Count
12
92
Transfer next count area (eight bytes) from the drive to
Next record count area or
main storage.
first count area after RO
Byte 0 = Flag.
Read Home
1A
9A
Transfer five bytes (FCCHH) to channel
Byte 1 =Cylinder address.
Address
Byte 2 = Cylinder address.
Byte 3 = 0.
Byte 4 = Head address.
Read Initial
02
-
Recalibrate to cylinder 0 and head 0, search for index
First data area after RO
Program Load
point, and read R1 data from the drive to main
(see Note 3)
storage.
Provide one byte of angular position information, which
is used by a subsequent Set Sector command. When
Read Sector
22
-
not chained from a Read, Write, or Search CCW, the
(see Note 4)
byte transferred is the angular position required to
access the last record processed on the drive. When
chained, the byte transferred is the angular position
of the record used in the previous CCW.
Note 1:
If
the KL equals 0 the command is executed the
Note 3: A Read IPL command cannot
be
preceded by a
same as a Read Data command.
Set File Mask command in the same chain.
Note 2: When chained from a Search HA or Read HA
Note 4: Causes loss of orien'tation.
command, the Read RO command is executed
immediately and does not initiate a search for
index point.
16 3330 Disk Storage
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