1
$\begingroup$

Consider a base 16 adder. How can I modify the adder so that it can perform a base 8 addition?

I expect this question will appear in my exam tomorrow; if anyone can give me a hint or a solution, I'd be grateful. I've tried searching the net and my textbook to get some insight, but nothing is clicking.

my textbook digital design 5th morris mano

$\endgroup$
  • $\begingroup$ Perhaps it helps if you think about it in decimal. Suppose you have a machine that can add two 2-digit numbers. How can you use it to add two 1-digit numbers? $\endgroup$ – Yuval Filmus Dec 30 '14 at 6:41
2
$\begingroup$

Assumptions/Statements: A base 16 adder: an adder that adds two 4-bit binary numbers I1 and I2 and outputs the 4-bit result R and a carry bit C

To use as a base 8 adder (as above) discard the Most Significant Bit from both I1 and I2 (i.e. ground/zero them). Now your inputs are base-8. From the output discard the Carry bit C it will always be zero. Your new Carry bit will be the Most Significant Bit from result R. Your new result will be the 3 least significant bits from R.

Please check Assumptions/Statements are in accordance to your book!

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.