CAIS 265
Assignment #2
(Worth 100 points)
Build a Logisim circuit as shown in the picture below.
The circuit performs 4-bit BCD addition and 4-bit BCD subtraction. The addition and subtraction
use A3 A2 A1 A0 and B3 B2 B1 B0 to perform A+B and A-B at the same time. The two
numbers should be entered through the pins shown at the top of the circuit, and respectively
displayed using two 7-segment displays and corresponding 7-segment decoders. The addition
and subtraction results are shown on the LEDS (S4 S3 S2 S1 S0 and D4 D3 D2 D1 D0 as shown
above).
The addition must be performed using 4 1-bit full adders that you built using K-mapping.
The subtraction must be performed using 4 1-bit full subtractors that you built using K-mapping.
You must build your own 7-segment decoders using K-mapping. The 7-segment display should
show numbers in the following pattern.
The 7-segment decoder, the 1-bit full adder, and the 1-bit full subtractor must be designed as
sub-circuits within Logisim, and instantiated on the main design area for building the circuit as
shown above.
To submit by the beginning of class on Tuesday (October 4, 2016).
1. Paper submission showing the K-maps and the minimized function based on the K-maps
for the subtractor’s Bi and Di, and also for the 7-segment decoder’s a, b, c, d, e, f, and g
outputs.
2. Submission of the Logisim circuit (.circ file) on Plato’s menu for this homework.