Half$-$Adder and Full$-$Adder subcircuits

In this exercise, you are going to create a Half$-$Adder subcircuit which is very much like a function

$($a$.$k$.$a$.$ subroutine$)$ in a programming language. The purpose of creating a subcircuit is just like

those of creating function in a programming language.

$$ Modularized approach for efficient circuit design

$$ Reusability of circuits

$$ Maintainability of circuits

$$ Readability of circuits

$1.$ First read the $$Subcircuits$$ section in Logisim Reference.

$$ Select Help$$Tutorial from the menu bar

$$ Expand Subcircuits

$$ Read all subsections but at least the first

two sections, $$creating circuits$$ and $$using

subcircuits$.$

$2.$ Now, let$$s create a subcircuits for Half$\_$Adder

$$ Click Project$$Add Circuit menu item from the menu bar

$$ Provide $$Half$\_$Adder$$ in the Circuit Name

textbox then click on OK

$$ This will add a new circuit $($Half$\_$Adder$)$ In

the navigation panel.

$$ Then double$-$click to the main Canvas.

$$ Select the entire half adder circuit on the

canvas.

$$ Copy & paste the selected half adder circuit in

the Half Adder subcircuit window.

$$ Make sure the data bits of all gates and

inputs$/$outputs are set to $1.$

$$ That$$s it$.$ You just created a $$Half$\_$Adder$$ subcircuit.

CSCI$1510$ LAB $4$ Adders and MUXes

University of Colorado

Computer Science and Engineering Page $4$ of $6$

$3.$ With that, now let$$s create a $$Full$\_$Adder$$ subcircuit

$$ Follow the same process to create a new subcircuit named $$Full Adder$$

$$ Double$-$click the $$Full$\_$Adder$$ subcircuit.

$$ In the empty canvas, add $2$ Half Adders by clicking and dragging the $$Half$\_$Adder$$

subcircuit into the Canvas

$$ Add an OR gate.

$$ Add inputs and outputs.

$$ Now properly wire them

$$ Simulate the full adder with the Poke tool.

$$ Now, you just created a Full Adder subcircuit.