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P Data
185
Q Data
+
52
237
Beginning Data
MARl 0
0
I
3
I
5
0
(2)
1
P Digit (Units)
1
Q Digit (Units)
5
CD
(
I
MARl
0
0
3
8
-
0
1
P Digit (Tens)
1
Q Digit (Tens)
0
1
I
MAR
I
0
0
3
CD
1
P Digit (Hundreds)
3
7
5
Zero Insert
0
Q Digit (Hundreds)
2
+
1 Carry from Step 7
Figure 59.
Add Operation
9.
There is no
Q
hundreds digit, but a zero is in-
serted internally. The zero, together with the
carry from Step 7, causes a 1 to go into the
units position of
MAR.
10. The sum (2) which is located at 00311 of the
Add table, replaces the P hundreds digit.
Figure 60 shows how OR-1 and OR-2 share
MAR
in providing locations of data in core storage. They
are decremented since this is a digit-by-digit opera-
tion. OR-3 retains the P address for sum recomple-
ment, if necessary.
2
)
5
)
Add Table
New P Data
-I
0
.,
1 8
7
\
0
I
Add Table
I
m
."
1
3
7
'\
0
I
Add Table
I
III
•
:2
3
7
,
®
I
Circled numbers refer to
numbered steps in text
The Q data digits are routed through the Digit and
Branch register to the units position of
MAR
for de-
velopment of the Add table addresses.
The P data digits are routed through
MDR
to the
tens position of
MAR
for development of the Add table
address.
The number 003 is automatically inserted in
MAR
for the three high-order positions of the Add table
address.
MAR
is used to address the Add table. The
sum looked up in the Add table replaces the P data.
69
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