Would my breaks fail if my alternator was broke?

my power steering and breaks failed would it be the alternator itself or the alternator belt. i jumped started the car and a half mile down the road everything went but after it went the lights was still on but very dim and was still able to roll up and down the electric windows. i know it is not the battery i just need to know if it the alternator itself or the belt. i have a 93 plymouth voyager.