Figure 13. Read Commands - IBM 3350-A2 Reference Manual

READ COMMANDS
Command Code Function Data Read
'
Single Multi-
Track track
Read Data Transfers data area of record from drive to main First data area after ad-
storage.
dress marker or data
06 86 area of record chained
from count or key of
same record.
Read Key and Data Transfers key and data areas of record from drive to First key and data areas
main storage. after address marker or
OE BE
If KL = 0, same as Read Data. the key and data areas
that were command
chained from the count
area of the same record.
Read Count, Key,
1E 9E
Transfers count, key, and data areas of record from Next record or first re-
and Data drive to main storage. cord after RO.
Read Record Transfers RO (count, key, and data) from drive to main Record Zero (RO).
Zero (RO)
16 96
storage.
If chained from Search HA or Read HA, is executed
immediately with no search for index.
Read Count Transfers next count area (8 bytes) from drive to main Next record count area
12 92 storage. or first count area after
RO.
Read Home Address
Transfers five bytes (FCCHH) to main storage. Byte 0 =Flag
Byte 1 = Cyl Addr
1A 9A Byte 2 = Cyl Addr
Byte 3
=
0
Byte 4 = Head Addr
Read Initial Recalibrates to cylinder 0, head 0, searches for index First data area after RO
Program Load
02
point, and reads R1 data from drive to main storage. on cylinder 0, head 0.
Cannot be preceded by Set File Mask or Space Count
in same chain.
Read Sector Transfers one angular position byte used by next Set One byte of angular
Sector. If chained from a read, write, or search CCW,
position data.
22
is position of the record used in the previous CCW. If
not chained, is position required to access the last
record processed by the drive.
Resets orientation information.
Read Multiple Count, Transfers remaining records on track to channel. Since Starts at count field of
Key, and Data number of bytes unknown, CCW count should be larger next record (except RO).
5E than the longest track length and SILi bit should be on
to suppress incorrect length.
Command retry may be affected.
Figure 13. Read Commands
28 IBM. 3350 Reference Manual