8 bit adder/sub with 4 bit ripple adder and muxes only

In summary, the conversation is about coming up with a minimal solution for creating an 8-bit adder/sub using only one 4-bit ripple carry adder and muxes. The proposed solution involves using the ripple carry adder for the first 4 bits and then using full adders built with muxes for the next 4 bits. However, this would require 8 muxes, and the person is seeking suggestions on how to improve or simplify the design. They are also asked if the subtractor needs to be implemented and for a block diagram of the initial solution.
  • #1
hime
26
0
Hi
I'm having trouble with coming up with a minimal solution to this problem: create a 8 bit adder/sub using only one 4 bit ripple carry adder and muxes. This is what I'm thinking but I don't know how to make it any bit simpler:

We can calculate the sum of first 4 bits using the ripple carry adder and then calculate the sum of the next 4 bits(bits 4-7) using full adders built with mux's. A full adder needs 2 muxes(one for sum output and another for carry out) and this means I need to use 8 mux's to calculate the sum of bits 4-7...any hints on how to improve on my idea or how to make this design more simpler? Thanks
 
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  • #2
hime said:
Hi
I'm having trouble with coming up with a minimal solution to this problem: create a 8 bit adder/sub using only one 4 bit ripple carry adder and muxes. This is what I'm thinking but I don't know how to make it any bit simpler:

We can calculate the sum of first 4 bits using the ripple carry adder and then calculate the sum of the next 4 bits(bits 4-7) using full adders built with mux's. A full adder needs 2 muxes(one for sum output and another for carry out) and this means I need to use 8 mux's to calculate the sum of bits 4-7...any hints on how to improve on my idea or how to make this design more simpler? Thanks

Are you saying you need to implement the subtractor too?

Can you show a block diagram of your initial solution? That may help us to suggest possible simplifications.
 

Related to 8 bit adder/sub with 4 bit ripple adder and muxes only

1. What is an 8 bit adder/sub with 4 bit ripple adder and muxes only?

An 8 bit adder/sub with 4 bit ripple adder and muxes only is a mathematical circuit that is used in computer hardware to add or subtract two 8 bit binary numbers. It is composed of a 4 bit ripple adder, which is used to add the numbers, and multiplexers (muxes), which are used to select the operation (addition or subtraction).

2. How does an 8 bit adder/sub with 4 bit ripple adder and muxes only work?

The circuit works by taking in two 8 bit binary numbers and using the 4 bit ripple adder to add them together. The result is then passed through a multiplexer, which selects either the sum or the difference (depending on the operation chosen) and outputs the final result.

3. What are the advantages of using muxes only in this circuit?

Muxes only circuits are simpler and more efficient compared to other types of adder/subtractor circuits. They require fewer components, which leads to a smaller chip size and lower power consumption. They also have faster operation speeds due to the parallel nature of muxes.

4. How is the carry bit handled in an 8 bit adder/sub with 4 bit ripple adder and muxes only?

In this circuit, the carry bit is handled by the 4 bit ripple adder. It is passed from one bit to the next, allowing for the addition of larger numbers. The muxes do not affect the carry bit in any way.

5. Can an 8 bit adder/sub with 4 bit ripple adder and muxes only be used for other operations besides addition and subtraction?

Yes, this circuit can also be used for other operations such as multiplication, division, and comparison. This is because multiplication and division can be broken down into a series of additions and subtractions, and comparison can be achieved by subtracting two numbers and checking the result.

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