The ND/NBC deal signed in 1991 is kind of the extension of the old deal it signed with the Dumont Network (the who?, now extinct) in 1949.
ND would have always had its own TV deal from 1949 until now if the nefarious NCAA had not extorted them.
"In 1951, five Notre Dame games were televised on the old Dumont Network. The package earned the school $55,000. Some athletic officials thought television would kill the live gate. Others wanted a piece of the tasty new pie. The NCAA soon moved into the picture, in part because many members were convinced that Notre Dame would monopolize the airwaves unless the NCAA negotiated a package for all its schools. Notre Dame decided not to fight it, and in 1952 began appearing on national telecasts in the NCAA package on a regular basis.
"There's no question that the NCAA TV committee was formed in 1952 to stop Notre Dame," said Beano Cook, an ESPN college football analyst who's followed the sport most of his life.
"Two schools were opposed to the TV contract -- Notre Dame and Penn, which had a big-time program. The other schools said fine, if you feel that way, play each other 10 times a year. Once Notre Dame signed on, it worked."
Here is a Wikapedia blurb about ND/Dumont and early TV coverage:
"Notre Dame would soon have an exclusive television deal with the DuMont Television Network starting in 1950.
What attracted Notre Dame to DuMont despite receiving higher bids from ABC and NBC, was DuMont's willingness to air educational programs on behalf of Notre Dame along with the football broadcast.
This triggered concern from NCAA members that television would hurt attendance. But Notre Dame argued that the contract with DuMont actually increased interest in their football program and the university.
On October 1, 1950, WSB-TV (channel 2), ABC in Atlanta, Georgia broadcast Notre Dame's game against the North Carolina Tar Heels from South Bend, Indiana via a coaxial cable.
WBKB (now WBBM-TV, channel 2), CBS in Chicago, Illinois aired Notre Dame's home games live with the aid of a microwave relay system that was fashioned by William C. "Bill" Eddy, Bill Kusack, and Arch Brolly."