### DIGITAL SYSTEMS CALCULATORS

Click on an input or a row on the truth table to change the addends.

## INFORMATION

A half-adder adds two bits and produces the sum and the carry as outputs. The operation performed by the half-adder is similar to the operation that occurs in the least significant bit when adding two binary numbers. There is no carry coming from the previous digit, we just add the least significant bits and write the result to the sum and provided that a carry occurs we pass it to the next digit.

The truth table of a half-adder is as follows:

In this table, x and y represent the addends, S represents the sum and C represents the carry to the next digit. The carry occurs only when both addends are equal to logic-1. The sum is equal to 1 when only one of the addends is 1, otherwise it is 0.

Two possible circuit implementations of a half adder circuit are illustrated above.

### WHAT IS HALF-ADDER LEARNING TOOL?

• Allows the user to select the input values and
• Illustrates the outputs on the circuits and the truth table.

### HOW TO USE THE HALF-ADDER LEARNING TOOL?

You can select the input values yourself or set them randomly.

• #### USER INPUTS

To toggle the input values between 1 and 0, click on the inputs of circuits or the block diagram.

Or click on any row on the truth table to set the input values.

• #### RANDOM INPUTS

The DIE ICON generates a random set of values for the inputs.