Control Commands - IBM 3340 Reference Manual

Command
Code Function
Data Transferred
Across Channel
No Operation
03
No action. Channel End and Device End are presented during
initial status.
N o n e
Seek
07
1 . S e l e c t s d r i v e .
2. Moves the access to the cylinder specified by the seek address.
3. Selects the head specified by the seek address.
Seek address
(six bytes)
Seek Cylinder O B
Space Count
OF
When chained from a Read, Search, Write or Space Count
command, this command locates the start of the next count
area (including R0), spaces over the count area, and ends
with Channel End and Device End in the gap before the Key
area.
When not chained, Space Count searches for index, clocks
over gap 1. Home address, gap 2, and spaces over R0 count.
Operation ends in the gap following the R0 count with
Channel End and Device End.
Three bytes used as Key
Length (one byte) and
Data Length (two bytes)
for the next command.
Recalibrate
1 3 Moves the access to cylinder 0 and select head 0.
N o n e
Restore
t 7
No action. Zero initial status is followed by final status of
Channel End and Device End.
Seek Head 1 B
Selects the head specified by the seek address.
Six address bytes. Only
the five low-order bits
of the sixth byte are
used for the seek
address.
Set File Mask
1 F
Sets file mask to indicate permitted Write, Seek, and
diagnostic commands.
One byte of file mask
data.
Set Sector
23
U s e d o n d i s c o n n e c t e d c o m m a n d c h a i n i n g c h a n n e l s t o e l i m i n a t e
the need for the channel to maintain connection with the
storage control while waiting for the selected record to reach
the head.
Note: lf the RPS feature is not installed on the addressed 3340,
this command returns Channel End and Device End together in
final status. No operation is performed and track orientation
is destroyed. All 3344 units have RPS.
One byte specifies
angular track position
(0-63)
CONTROL COMMANDS
Control Commands 27