help me

Well, at least this homework problem is out in the open. This isn't a combinatoric logic problem, because lines 2 and 4 have the same inputs and a different output. It sounds like you're being asked to design a small state machine, or at least something with gates and feedback.

As a Boolean logic problem, this table is both incomplete (it's missing input state T=0, B=1) and self-contradictory, as above. Please check it.

Cheers

Phil Hobbs

Do you mean, sometimes 1 & 0 yields 1, and sometimes 1 & 0 yeilds 0?

How do you decide which one to choose in any given instance? It might simply be impossible, without more information.

Are you sure you copied the test question down accurately?

Thanks, Rich

Maybe T and B both have to go high to make Y go high, and they both have to go low to make Y go low. So look at the list as a sequence rather than a plain truth table.

If you stated it correctly, B is irrelevant for an output change from 1 to 0. The output changes from 1 to 0 only when T changes from 1 to 0.

Going the other direction on the output, from 0 to 1, apparently requires that B change from 0 to 1.

So, guessing set and reset, based on incomplete information.

Ed

Your problem can't be solved with pure combinational logic.

Please make sure you haven't made a typographical error.

If not, have you had "sequential" logic instruction in your class?

...Jim Thompson

Problem is not clear so is your question. Information incomplete and/ or wrong.

petrus bitbyter

Do it like this...

...Jim Thompson

Oops!

I think you'd better restate your homework problem. ;^)

Looking at your circuit I'm not seeing how you make T.*B = 0 & 1 at the same time. ;^)

it just needs a little feedback.

Y = B or ( T and Y )

lots of people missed the word "cycle" I took the list to represent the steps in a repeating cycle.

I don't think any instructor would word a problem like that so it's probably not homework.

Yep, Called a Set/Reset Flop, as I posted two days ago...

Message-ID:

...Jim Thompson

It's solved as a Set/Reset flop...

0,0 Resets

...Jim Thompson

That seems a reasonable interpretation, but in that case there's insufficient data to make any useful comments. Is it a state machine? Is it clocked? What is supposed to happen if the T & B inputs are both high? What's the power up state?

Everybody's missed the point that OP is a googlie.

We'll never hear from him/her again.

Cheers! Rich

Is=20

Is=20

yes. no. Y becomes 1. undefined.

Sorry about forgetting the content with the previous post.

I posted a solution...

Newsgroups: sci.electronics.design Subject: Re: help me Date: Thu, 07 May 2009 07:54:14 -0700 Message-ID:

and white-listed the OP.

Never saw any response. So I'd guess it was homework, and the two days I took to get around to playing with it for a few minutes was beyond his deadline ;-)

...Jim Thompson