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Figure
21.
111M
17 13
Manual
Entry Unit
M ude
Switches. The two rotary
sw itches at
the left
of
the two
rows of
five data
swi
tches
are
designa ted
Mode switches
1
and 2.
respectively.
Each switch
has
ten digit positions
(0-9).
These positions
are
labeled
by the user to identify for the process
operator
the
nature
of
the information to be
entered
through the
data
switches.
The program
can
identify the nature
of
information
entered
through the data
sw itches
by
an
ana lysis of
the digits
entered
by the mode
switches.
End-oJ-M
essage.
In
addition
to its function
as a
data
sw itch.
the
switch at
the right
end of
the bottom row
of
switches a lso serves as an
end-of-message indication.
Transmission
of
data from this
switch
removes the unit
from response
status and
turns
oft
the
Execute and
Enter lights. To initiate the next interrupt. the
Exe-
cute
button
can
be pressed
or Mode switch
1
can
be
addressed
by the program.
Enter
Light. This light is used to signal the process
operator when the program requests input data. The
Enter light
can
be turned on by
addressing
it with
a
Select Input Channel instruction if the program is
to immediately
start
reading the data
already
in the
switches.
or the Enter light can be turned on by
ad-
dressing it with a Write Numeric
Output
Channel
instruction if the operator
is
to enter data before the
read operation begins. The Enter light
is
turned
off
when the unit is removed from response
status.
If the
Select Input Channel instruction is used to turn
on
the Enter light, the Data
Ready
indicator will be
turned on
and
the Data
Ready
interrupt
initiated.
The
32
Write Numerical
Output
Channel instruction
does
not
turn on
the Data Ready indicator
or
initiate the
Data Ready interrupt.
Therefore.
in programs
where
it is desired that
the operator enter the data and
then
initiate the interrupt. the latter instruction
w
ill
be used.
PUWe1'
On
/
Off
Switch and Light. This swi
tch is used
to
contro
l
electrical
power to the
Manual Entry Unit.
The
light
serves as a
visual indicator that power is
on.
IBM 1714 Sense Switch Unit
The Sense Switch Unit (Figure 22) allows
the
process
operator
to
provide
data
to
the program through twelve
toggle switches. The program can sense
the
ON
or
OFF
condition of each switch
upon
command. Switches are
addressed
in
groups of three (Figure 23) . Therefore.
four
consecutive addresses
are required
for
the twelve
switches. one
for
each group.
Since
each group of
switches
is individually
addressable. each
may be read
in
any order as
directed by the program. Program
analysis of a character (n umerica
l
digit) to be read
will
reveal the
switch settings of
the individual
switches of
a
group.
In
each
group of
three
switches,
the first
one stores
a 4
bit if it is
on; the second. a
2 bit;
and
the third.
a
I
bit.
If
a switch
is
off.
no bit is
stored. Therefore. at each
three-switch
address. a character
is transmitted to
de-
note the
corresponding combination of switches
ON
as
shown
in
Table
2.
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