In rare cases, you may find that an equivalent XC4000E device
does not configure when dropped into your existing XC4000 socket.
You may encounter this problem if your design:
1. Configures in peripheral, master parallel,
or master serial mode
2. Uses one or more mode pins as signal pins, AND
3. Has pull-down resistors over 5k on one or more mode pins.
Note that all three of these criteria have to be met for
this problem to occur.
Change the high-resistance pulldowns to resistors of 5k or below.