# Computer Organization and Design problem

Discussion in 'Homework Help' started by DesmondMilez, Aug 14, 2012.

1. ### DesmondMilez Thread Starter New Member

Aug 14, 2012
1
0
Hi everyone.
I am new to this forum and i joined cause i am really stucked with all of the counters and flip-flops.

I am preparing for an exam in 20 days so i need help with an exam question that was on the previous exam which i failed

It says :

" Using Johnson's counter (twisted ring counter) create a binary UP counter modulo 8. Use T flip-flops and any logical gates you want. "

I know i should create a truth table first but the problem is i dont know if i should use 4-bit or 3-bit counters.

Then in the truth table i should evaluate T and after that comes the Karnaugh map minimization.

Last thing i have to do is to draw the circuit and get all the points

So guys i need any hints that can help me solve this problem. I will appreciate that a lot. Thanks and sorry for bad english.

2. ### WBahn Moderator

Mar 31, 2012
18,092
4,918
Well, let's tackle it one step at a time.

Q1) First, make sure you understand what you want. The end goal is a modulo-8 counter. How many different states does this imply?

Q2) Then, make sure youi understand what you basic building block is. If you are using a Johnson counter with N bits, how many different states are there? If you need to, start with a 1-bit counter, then a 2-bit and 3-bit counter and count the states and see if you can figure out the pattern that sets the relationship between how many stages there are and how many states there are.

Q3) Given the answers to Q1 and Q2, how many stages do you need in the counter to get a modulo-8 UP counter?