When their kids were all still quite young (myself about 7, my sister about 5, my brother about 3, and before the last one came along) my dad worked 2 jobs. During the day, he worked for the University of Utah doing something that I didn't understand because I was just a kid. At night, after he was done working at the college, he would deliver pizza for Dominoes. One of my most vivid childhood memories is that of laying in my bed, listening for Dad to come home from work. I knew that I could usually count on cold pizza for breakfast in the morning.
My mom's job as a school teacher allowed her to spend quite a bit of time with us.