Understanding Half ADDER and Full ADDER (UHAFA)

The Adder circuit is a digital electronic circuit that is used to add two numbers (in the binary number system), meanwhile in computers the adder circuit is found in the microprocessor in the ALU (Arithmetic Logic Unit) block. The number system used in adder circuits is:

Binary number system (has base/radix 2)
Octal number system (has base/radix 8)
Decimal number system (has base/radix 10)
Hexadecimal number system (has base/radix 16)

Objective

So that students are able to understand how half adder and full adder circuits work.
So that students are able to make half adder and full adder circuits from basic logic gate combination circuits.

However, among the four systems, the most basic is the binary number system, while to implement negative values, the complement number system is used. BCD (binary-coded decimal).

Note! - In order for you to understand the basic concept of adder circuits, first master the conversion techniques between the number systems above. You can read more HERE .

Discussions about adders usually start from half-adder then full adder after that is ripple-carry-adder.

Half adder

Based on two inputs, namely A and B, the output is S(sum), S or sum will be calculated based on the implementation of the XOR logic operation of A and B. In addition to the S(sum) output, there is another output that we know as C(carry), while the C(carry) output is produced from the implementation of the AND logic operation.

The principle is that OUTPUT S states the result of adding inputs A and B, while C states the MSB (most significant bit or carry bit) of the addition.

Full adder

Based on the two inputs as above (half-adder), the working principle is also the same as the half-adder, except that the Full-adder is able to accommodate the carry from the previous addition result. So with the carry, the number of inputs can be 3 at any time (depending on the condition of the carry, whether it is active or not).

Practical Steps

Prepare the equipment and materials needed.
Implement the circuit schematic to be tested into the project board and ensure all connections and wiring are good and correct.
Connect the adapter to the power outlet, then check the output from the adapter.
Provide input with logic 0 by connecting the input to ground and 1 by connecting the input to the positive power supply (+5v)
Perform step 6 according to the truth table requirements.
Observe the changes in the LED and record the results in the lab results table.
Repeat steps 2 - 6 for the other practical series.
Finished.

EXPERIMENT I (Half Adder)

Truth Table

Here is a Half Adder Demo to see the truth table above.

https://youtu.be/IAYG6y3zyGY

If you want to try it yourself, please download the circuit at HALF ADDER.ms11(60KB)

EXPERIMENT 2 (Full Adder)

Truth Table

Here is a Full Adder Demo to see the truth table above.

https://youtu.be/CgfEXu3MdxA

If you want to try it yourself, please download the circuit at FULL ADDER.ms11(64KB)

Evaluation & Conclusion

EXPERIMENT 1

Based on the basic theory and the results of experimental observations, the Half Adder circuit can be arranged using an X-OR-forming TTL IC and an AND-forming TTL IC, where the XOR GATE output is SUM, while the AND GATE output is CARRY. Meanwhile, the truth table shows that, if the condition of both inputs is high (1), then the carry out will also be high (1) and if only one input is in high condition, then the high (1) output only reaches SUM.

EXPERIMENT 2

Based on the basic theory and the results of experimental observations, the Full Adder circuit can be arranged using 2 X-OR gates, 2 AND gates and 1 OR gate, where the principle is almost the same as the Half Adder, namely "when both inputs are high (1), the high output will be in CARRY, while if one of the inputs is high, the high output will be in SUM. Meanwhile, because the full adder has 3 inputs, if all (three) inputs are in high (1) condition, all full adder outputs will be high (1) too.

Netizens

Comment 1

MUHAMMAD FAIZ || Nov 17, 2015, 18:20:00 = very good article, but the download link is dead, bro
SALEHATUN NISA || Jan 20, 2016, 16:06:00 = how to calculate it??
DERRI PRATTAMA || Apr 7, 2016, 22:15:00 = Bro, what software is used to test the truth table above?
WAYAN G. YOGA || May 15, 2016, 21:56:00 = thank you very much for the information
ANONYMOUS || 9 Jun 2016, 22:58:00 = full adder can't be downloaded
ANONYMOUS12 Jun 2016, 12:21:00 = it says you do not have access to this page
NARUMONKEYD.ARMA Oct 30 2016, 14:13:00 = permission to copy and paste, for assignments, please include the link
UNKNOWN || 20 Dec 2016, 17:02:00 = can I ask?? what application is from half adder?? thanks

Response 1

Hello Muhammad Faiz, the download link is still active, so here's how to download it: 1. Click the download link 2. Skip the ad by pressing the SKIP button in the upper right corner (the button will not appear before the timer reaches 0 seconds) 3. After that, the file will automatically download, easy, isn't it? Thank you, good luck.
Hello SALEHATUN NISA, Comparison of manual vs computer solutions is HERE , Happy learning and good luck4.
Hello DERRI PRATTAMA, we use Multisim, a development of Electronic Workbench, a product of National Instrument, to download the application, please visit www.ni.com
Hi Wayan G. Yoga, you're welcome.
Yes, bro, after clicking the download link >> (wait a few seconds) then click SKIP >> then the file will automatically download.
I tried it and it still works, bro. The files have been downloaded in full (half and full). But if you still can't do it, please just PM me on FB, bro. I'll send you the original file.
Hii NARUMONKEYD.ARMA, please, with pleasure, and happy learning10.
Create ALU Design, as found in processor and microcontroller architecture. Not only that, half adder is also used for full adder architecture design, as found in CMOS IC, IC 4008, IC 54F283, etc. and has been widely produced by semiconductor companies in various packages. if asked to make what? the answer cannot be instant, but what is clear is that its characteristics cannot be used directly to make a product. And in fact, almost all electronic devices are inseparable from the role of half / full adder.

Introduction to the 4 BIT & 8 BIT FULL ADDER Circuit

An Adder is a digital electronic component used to add two numbers (decimal) using the binary number system. In computers and microprocessors.

Adder is usually located in the ALU (Arithmetic Logic Unit). The number system used in the addition process, in addition to binary numbers, is also the complement number for negative numbers and BCD (binary-coded decimal) numbers, and excess-3. If the number system used is 2's (binary complement), then the addition and subtraction operations will be very easy to do.

Parallel Adder circuit is a circuit that adds two numbers (either octal, decimal or hexadecimal) that have been converted into binary form. For example, assume there are two registers A and B, each register consists of 4 bits, so we can define it as follows: A3A2A1A0 and B3B2B1B0 [binary].

The Parallel Adder circuit consists of a Half Adder (HA) on the Least Significant Bit (LSB) of each input and several Full Adders on the following bits. The working principle of the Parallel Adder is as follows: addition is done starting from the LSB. If the result of the addition is a decimal number "2" or more, then the excess bit is stored in Cout, while the bit below it will be output to Ó. And so on to the Most Significant Bit (MSB).

Objective

So that students are able to understand the logic concept of 4-bit Adder and 8-bit Adder.
So that students know the difference in performance between 4-bit and 8-bit adders.

Full Adder 4 bit datasheet on IC CMOS 4008