Motorola CMOS Logic Manual page 487

One MC14560B and one MC14561B permit a BCD digit to
be added to or subtracted from a second digit, such as in
the typical configurations in Figures 2 and 3. A second
ADD/SUBTRACT
ZERO
TRUTH TABLE
Zero Add/Subtract Result
0 0 B plus A
0 1 B minus A
1 X
X = Don't Care
MOTOROLA CMOS LOGIC DATA
TYPICAL APPLICATIONS
MC14561B
A1
A2
A1
A3
A4
COMP
COMP
Z
B1
MC14561B
A1
A2
A10
A3
A4
COMP
COMP
Z
B10
B
Figure 2. Parallel Add/Subtract Circuit (10's Complement)
MC14561B permits either digit to be added to or subtracted
from the other, or either word to appear unmodified at the
output.
F1
MC14560B
C in
S1
F2
A1
A2 S2
F3
A3
F4 A4
S3
B1
B2 S4
B3
C out
F1
MC14560B
S1
C in
F2
A1
F3 S2
A2
A3
F4
S3
A4
B1
S4
B2
B3
C out
B4
UNITS
TENS
MC14561B
6–449