The addition of a Schmitt trigger prevents that from being a problem. There is one issue that some customers have faced. The specification for input rise time is 20 ns. However, some customers are using a RC circuit on the reset input that produces substantially longer rise times. This problem may be aggravated when the reset signal goes off board, adding to the capacitance.
Parameters vary from lot to lot.
But generally, the input threshold for reset on the TK68HC24 is higher than both the original Motorola 68HC24 and that on the 68HC11 microprocessor. IF this is the case, and IF reset has a slow rise time, THEN the 68HC11 processor can become active while the TK68HC24 is still in reset. We have seen a case where the processor wrote initialization data to the TK68HC24 while it was still in reset, which caused a system failure. The best fix is to not violate the input rise time specification. You can call as well, but a written question gives us the opportunity to provide a more detailed answer.