I'm using the popular TL866II Plus programmer to read from the chip. I see in the datasheet that it has lock bits which can disable the verify (read) function, but I'm not sure if that causes an attempted verify to yield all FF's, or if it would give an error of some kind.

In the situation where the lock bits are in fact set, is there any known way to bypass them and dump the firmware from the chip? Keep in mind, this chip came from a very rare board, and that chip is the only copy I have of the program, so I don't want to risk erasing it.

  • Did you remove the chip from the board or trying to dump it in-circuit?
    – Igor Skochinsky
    Sep 16, 2021 at 11:25
  • @IgorSkochinsky I removed it from a socket on the board. Also, it might be worth mentioning that the same result occurs if I attempt the dump without actually having the chip connected to the programmer.
    – Sparkette
    Sep 16, 2021 at 19:41


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