Is this an asynchronous down counter?

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SUMMARY

This discussion confirms that the circuit in question is indeed an asynchronous binary down counter, assuming all J and K inputs are connected high. However, it highlights significant issues with propagation delays that lead to incorrect output states during clock pulses. The simulation results indicate numerous glitches in the output sequence, making it unsuitable for serious counting applications, although it can function as a simple divider.

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[PLAIN]http://img30.imageshack.us/img30/3306/counterty.jpg

Is this an asynchronous down counter, or is it nonsense? (Assuming all J and K inputs are connected high)

Trivial question, I know :-)
 
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Yes, it is an asynchronous binary counter that counts downwards.

However, it would have problems with propagation delays and these would cause the outputs to be wrong for a short period after some of the clock pulses.

I put the circuit into a simulator that includes propagation delays and it showed up a large number of glitches in the output.

So, you get the following (with glitch outputs shown in brackets):

0
(1)
(3)
(7)
F
E
(F)
D
C
(D)
(F)
B
A
(B)
9
8
(9)
(B)
(F)
7
6
(7)
5
4
(5)
(7)
3
2
(3)
1
0

So, it would be OK just as a divider but not for any serious counter application.
 

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