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suppressed and additional logic is wired in by an IBM custo-
mer engineer.
While reading 8-track tape when the track-suppress switch
is on, it is possible to read the shifted binary-coded decimal
(BCD) code while still maintaining odd parity checking, and
to consider seven-hole punched characters (track 1 to 7) as
delete characters. If track 8 is punched, then it is necessary
to wire this track for suppression.
Parity Switch
The setting of the three-position parity switch permits a
choice of parity checking within the 2671/2822. When set
to NONE, no parity checking takes place. When set to
EVEN, even-parity checking circuitry is active for all tracks
of the tape being used. When set to ODD, odd-parity check-
ing circuitry is active for all tracks of the tape being used.
Regardless of the setting of the switch, all tracks are trans-
mitted to the System/360 with odd parity. When the width
of the tape is such that a track does not exist, a 0-bit is
transmitted for that track position.
Delete characters are not parity checked when the delete
switch is on.
2671 CONSOLE PUSHBUTTONS
Power-On-and-Reset Pushbutton
If the remote/local switch (located on the CE panel) is set
to LOCAL, pressing the power-on-and-reset pushbutton
supplies ac and dc power to the 2671.
For units fitted with the isolation feature, the pushbutton
is active only when the degate switch (located inside the
unit) is set to ON. With the remote/local switch set to
REMOTE, the pushbutton is inoperative and power is
supplied under the control of System/360, but the push-
button still retains its reset function. The change from local
to remote powering, and vice versa, can only be made by
the IBM customer engineer.
For units not fitted with the isolation feature, the
power-on-and-reset pushbutton must not be used when the
2671 is in local mode to avoid channel disturbances (unless
the System/360 is in a wait condition).
Pressing the pushbutton (even when the power is on)
resets the 2671, provided that no command is in progress.
Power-Off-if-in-Local Pushbutton
If the remote/local switch is set to LOCAL, pressing the
power-off-if-in-local pushbutton removes ac and dc power
from the 2671. For units fitted with the isolation feature,
the pushbutton is active only when the degate switch is set
to ON. When the remote/local switch is set to REMOTE,
the power-off-if-in-local pushbutton does nothing, and
power can only be removed under control of System/360.
The change from local to remote powering, and vice versa,
can only be made by the IBM customer engineer.
Provided that the 2671 is in local mode and the isolation
feature is fitted, the pushbutton may be used in powering
procedures, as described on a label attached to the unit.
It is advisable to turn the power off when the following
conditions are satisfied:
1. Unit not last on the channel.
2. Remote/local switch set to LOCAL.
3. No immediate use of 2671 expected.
Start Pushbutton
Provided all other ready conditions are satisfied, pressing
the start pushbutton puts the 2671 in a ready condition,
turns on the ready lamp, and signals the System/360 that a
paper tape read operation can be initiated.
Stop Pushbutton
In a nonprocess runout (NPRO) operation, pressing the
stop pushbutton stops the tape immediately and turns off
the NPRO lamp.
If the 2671 is ready, but not reading, pressing the stop
pushbutton turns off the ready lamp immediately.
In a read operation, the ready lamp turns off only after
the read operation is completed, regardless of the status of
the 2671 at the completion of the read operation.
End-of-File Pushbutton
When several rolls or strips of tape belonging to the same
file have to be read, the end-of-file pushbutton must be
kept in the OFF position until the last roll or strip of tape
is inserted in the 2671. Then the pushbutton is pressed and
the end-of-file lamp turns on; the 2822 is conditioned to
signal to the channel that the last tape of a file has been
read.
The 2671 remains in the ready state until the channel
issues a new command, when the status unit exception is
sent and the 2671 becomes not ready.
NPRO (Nonprocess Runout) Pushbutton
The NPRO pushbutton, when operated, feeds tape without
processing, if the following conditions are satisfied:
1. Power on.
2. Ready lamp off (if on, press stop pushbutton).
3. Tape properly loaded (load lamp off).
4. Channel operating or unit in the CE mode (off-line).
The tape continues to move forward until the stop push-
button, load switch, or power-on-and-reset pushbutton is
operated, or an end-of-tape condition is detected, or a
check condition occurs (tape jam in the 2671 or in one of
the stackers, or overstep). The NPRO pushbutton is used to
rewind a roll of tape after it has been processed, provided
that the roll of tape was previously moved from the take-up
feature to the supply feature.
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