so, the output of QA and QB, will go to clear pin won't it? but I also need the output of QA and QB to load the chips, and start counting right?
btw, just wanna to know, what software are using to draw the schematic? I'm looking for user friendly software to draw my schematic and do my simulation..

 

It will draw, but not simulate. I am a visual person, so I need something to illustrate my points fast. Doesn't keep me from making bonehead mistakes, but it does illustrate them for all to see.

When a counter is reset it will go to 0000. The process is automatic. These chips (because of their preset abilities) tend to make nice digital timepieces. Since they can count down as well as up even more so.

Bill's Index

Introduction and PaintCAD

LTSpice is free, and does simulate. Be prepared for a learning curve though. I don't use it myself, I use that bone between my ears.

 

can anyone here helps me with my project here's my problem actually

As a part of cadet pilot selection procedure in Digital Airlines, the candidates are required to go through a rigorous simulator exercise. Candidates are allowed 3 trials; and in each trial, they are given SCORES on a scale of 0-3. The candidate qualifies the test if he/she gets SCOREs of
1) 3 at least once, OR
2) at least a 2 at least two times, OR
3) at least a 1 in all the three trials
The SCORES are set on a 2-bit DIP switch and a TRIAL pushbutton is pressed to prompt the system to read the SCORE for that trial. After reading in the SCOREs for all the 3 trials, the system shows the result (PASS/FAIL using green and red LEDs) for exactly 3 clock cycles, following which the system gets ready for the next candidate.
Bonus:
1) As soon as a candidate qualify (for example, if the candidate scores 3 in the first trial, he is declared qualified immediately), the next candidate can undergo the test.