Hans van den Elsen wrote:
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in the AN461 is a circuit that uses an 74LS125. i've connected the 74LS125 in my circuit.
and after that i'm not be able to program my uC.

do i need this 74LS125??

Dunno. How have you wired it ! my copy of AN461 doesn't have a circuit with a LS125 in it.

Steve