IBM System 360 Operating Manual page 36

Auto-Fill Switch (with the 1051 Auto-Fill Special
Feature)
In the on position, fill characters (idle code) are
automatically generated by the 1051 during the
execution time of printer functions such as new line
and tab. Write commands are interlocked during
the same period of time. On read commands, the
idle codes are not read into storage.
In the off position, fill characters (idle code)
are not generated.
System Attend/Unattend Switch (1051 Model 1 Only)
This switch must be in the attend position for all
on-line operations, or the 1051 will not indicate an
operational condition to the 2030-1051 attachment.
1050 Intervention-Required Light (on 2030 Console)
This light turns on whenever a command execution
is terminated with an intervention-required condition.
It
is
reset by the next 1050 read or write command,
or by a 2030 system reset.
1050 Request Light (on 2030 Console)
This light turns on whenever the 1050 request key
on the 1052 is pressed. It is reset when attention
status is recognized by the attachment and accepted
into the unit status register.
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I/O Assignment Switches
The I/O assignment switches transfer the various
1050 I/O devices to the desired 1050 loop, or they
disconnect them from the 1050 completely. When
the 1050 home loop is switched to on-line operation
(CPU connect switch on), the devices that are to be
made available to the CPU must have their switches
in the home position.
Al ternate -C ode Key
When the alternate code key is held down while a
numeric key is pressed on the 1052, a 1050 control
character is generated.
Alternate Code--Zero (Cancel). Whenever the alter-
nate-code key and the zero key are pressed, a unique
cancel character is generated that terminates the
keyboard entry with channel-end, device-end, and
unit-exception statuses. The cancel character is
not read into storage.
Alternate Code--Five (EOB). Whenever the alter-
nate code key and the 5-key are pressed, an EOB
(End of Block) character is generated. This initiates
a normal end to the keyboard entry. The EO B
character is not read into storage. Alternate code
six (EOT) produces the same function as EOB.
For a description of other standard or optional
1050 lights, switches, and manual controls, refer
to IBM 1050 Operator's Guide, Form A24-3125.