dude your telling me the stuff i should be taking care of when i am half way through it.i am still at zerolevel.where should i start from?.i mean whats the theory behind using these counters to achieve this particular goal?

I think you are trying to accomplish far too much with very limited knowlege.

First start with the Volume IV Digital lessons at the top of this forum. Then start experimenting with simple gates AND, OR and so on. Maybe then try a counter. Don't worry about displaying anything just yet. Get a logic probe or build one. Understand how everything works then move on with your full project.

 

Is this homework?

If you don't want to deal with all of the count-down count-up stuff, you could always display two hex digits as three octal digits; just use a zero for the most significant bit.

 

There is a nice experiment with counters here

http://www.allaboutcircuits.com/vol_6/chpt_7/6.html

and seven segment displays here

http://www.allaboutcircuits.com/vol_6/chpt_7/9.html

I have always found that if you look at the whole problem as one big piece, it can be very confusing and almost impossible to understand. But if you break it into small pieces, it makes the whole thing much easier to understand.

 

ok i got it.it was simple.gosh if they had told me in the first place i wouldnt have suffered so much..i set both the binary down and bcd u counter.i feed in my 8 bit number in the binary counter and and it counts down while at th saem time the other bcd counter counts up and once the binary counter reaches zero the bcd counter is stopped!.rite?.thats what i made out of it...adn plz plz tell me how to cascade two 74ls193 chips so that they output 8 bit numbers.i tried to connect the carry of first chip to the down clock input of the other.is it the correct way to do it?.