Since the supply rail may be up to +15v, the device may be used to
    conveniently switch programming voltage and other such signals.
    Unfortunately, the switching threshhold for "standard" CMOS or 74HC
    parts is VDD/2; if VDD is 12 volts this means the switching thresh-
    hold is at least 6 volts--not something a normal port can deal with.

Um, 6 to 12 volts is well within the range of an "open collector" driver
like the 7407, or have those ceased to exist?

BillW