Digital Logic 8 Bit Full Adder Circuit

Click For Summary

Discussion Overview

The discussion revolves around the design of an 8-bit full adder circuit, specifically focusing on how to combine two 8-bit full adders to create a 16-bit adder. Participants explore the requirements and configurations necessary for this circuit, including the use of additional logic gates such as NAND and NOR.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • Some participants express uncertainty about how to approach the problem of combining two 8-bit full adders into a single circuit.
  • There is a question regarding the format in which the adders are provided (block diagrams, gate-level circuits, or code) and how this affects the design process.
  • One participant clarifies that the goal is to design a circuit that takes two 16-bit inputs and produces a 16-bit output, suggesting that this is distinct from simply having 16 individual 1-bit adders.
  • Another participant references a textbook definition of a half-adder and discusses the implications for combining full adders, indicating a potential misunderstanding of the components involved.
  • There is a query about the differences between full adders and half adders and how this knowledge might assist in the design process.
  • Some participants agree that 16 individual 1-bit adders do not equate to a single 16-bit adder, indicating a shared perspective on this distinction.

Areas of Agreement / Disagreement

Participants generally agree that 16 individual 1-bit adders are not the same as one 16-bit adder. However, there is uncertainty regarding the approach to combining the 8-bit full adders and the specific requirements of the circuit design.

Contextual Notes

Participants mention various formats for the adders and the potential need for additional logic gates, but there are unresolved questions about the exact specifications and assumptions underlying the problem.

Who May Find This Useful

This discussion may be useful for students or individuals interested in digital logic design, particularly those working on circuit design involving adders and related components.

ver_mathstats
Messages
258
Reaction score
21
Homework Statement
We are given two 8-bit full adders, we must create a circuit that will add 2 16-bit numbers.
Relevant Equations
-
I am unsure of how to approach this problem, we begin with two 8-bit full adders, is the goal to just combine them in some way so that it becomes one entire circuit while also adding NAND and NOR gates where necessary? By the end will we then have 16 1-bit full adders?
 
Physics news on Phys.org
How are you "given" them? As block diagrams, as gate-level circuits, as Verilog or VHDL code?

Can you show what you are given, and then comment on what a 16-bit adder looks like when you search for it on Google Images?
 
I read this as a circuit that has two 16 bit inputs and a single 16 bit output (plus a carry out bit, I guess?) that is the sum of the inputs. Your job is too design that circuit primarily using two 8 bit full adders plus simple logic if needed.

I don't think 16 1 bit adders are the same as 1 16 bit adder.
 
Last edited:
berkeman said:
How are you "given" them? As block diagrams, as gate-level circuits, as Verilog or VHDL code?

Can you show what you are given, and then comment on what a 16-bit adder looks like when you search for it on Google Images?
In the textbook that I'm reading Essentials of Computer Architecture by Douglas Comer a half-adder is shown with an or gate and an and gate, however for the practice questions we're given, we were now told one 8-bit full adder which can be drawn as a block is sufficient, not individual 1-bit adders which I just learned right now, so I may have a better understanding now by just learning this and have to somehow connect the two using NAND and NOR gates.
 
What is the difference between a full adder and a half adder? How do you think this could help combine 2 full adders together?
You do not need any extra gates
 
DaveE said:
I don't think 16 1 bit adders are the same as 1 16 bit adder.
Nor do I...
 

Similar threads

Digital Logic 4-bit Multiplier/Adder
  • · Replies 6 ·
Replies
6
Views
19K
MHB Optimizing Carry-Skip Adders for Minimal Delay
  • · Replies 3 ·
Replies
3
Views
1K
Engineering Full adder circuit using NAND v NOT, AND, OR v PLA logic
  • · Replies 1 ·
Replies
1
Views
5K
Comparator design using a 4-bit adder
  • · Replies 7 ·
Replies
7
Views
13K
Engineering Creating a 4 bit full adder logic circuit
  • · Replies 2 ·
Replies
2
Views
15K
Creating a full adder using a 3-to-8 decoder
  • · Replies 23 ·
Replies
23
Views
37K
Designing a 4-Bit Multiplier using Basic Digital Logic Components
  • · Replies 5 ·
Replies
5
Views
8K
Designing a 2-bit Comparator with NOR gates
  • · Replies 7 ·
Replies
7
Views
8K
Comp Sci Find the length of Robin's route
  • · Replies 8 ·
Replies
8
Views
2K
Engineering How Can You Solve Boolean Expressions Using Only NAND and NOR Gates?
  • · Replies 2 ·
Replies
2
Views
5K