$.$ Use Logisim to implement a $1-$bit adder.

$2.$ This $1-$bit Adder $($Adder$1.$circ$)$ preforms a binary addition. This adder is called a full

adder because it has $3$ inputs $($X$,$ Y$,$ and CarryIn$)$ and $2$ outputs $($Sum and CarryOut$).$

The $1-$bit Adder block diagram is shown in the following:

$1-$bit Adder Block Diagram

$3.$ Like Figure $3\mathrm{.}21$ in textbook, the truth table and the logic diagram for a full adder are

shown in the following:

FIGURE $3\mathrm{.}21$ The Truth Table and The Logic Diagram for a Full$-$Adder

Note that this full$-$adder is composed of two half$-$adder;

CarryOut $=$ XY $+($X xor Y$)$ CarryIn; Sum $=$ X xor Y xor CarryIn;

Adder$1$ Sum

Y

CarryOut

CarryIn

X