Andy Niel wrote:

With a watchdog, you need it to be reliable - not cheap!!


I disagree with your statement. Does the test of time qualify to reliability? If so then the 555 certainly does qualify.
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Andy Neil also wrote:

If it turns out that you have to redesign your circuit late in your design cycle because the 555 WD was unrealiable, that will certainly not be a "cheap" change in anyone's book!! :-0 


Here again I disagree. Nothing is more easier to reengineer than the 555. Should you find a bug in the hardware design there certainly is a fix for the 555. 

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All in all the 555 has proven it beats the socks off of most IC's just because of it sheer diversity. My two cents worth.
Regards,
Charles Bannister