I have four 16C74's that have been programmed MANY times.  I have not used
them for a while, but just recently thought I'd give them a try.  I loaded
them with some code and they seem to work..... well sort of.  They would
run for a while and then lock up for no apparent reason (they are driving
an LED display) sometimes they wouldn't even start at all.  I have tried
all four PICS with the same code, and they all do similar things, but I
can't get them to fail consistently.  The only thing that seems to make a
difference is how much I load the ports.  If I only fire a few of the LED's
at once they seem to lock up a lot less frequently (they still lock up
sometimes).  I have all of the LED's run through buffers, so I know I am
not loading the port TOO much.  Is this a sign that I should buy some new
PICS or am I missing something.



Thanks for any advise,

Zach

PS I am pretty sure that the code I am using is fine, because "sometimes"
it works ("sometimes" -- meaning I program all four PIC's with the same
code and one out of the four works).