For years I badgered my mother with questions about whether the Tooth Fairy is a real person or not. Her answer was always "Well, you wished for the presents and they came, didn't they?" I finally understood the full meaning of her reply when I heard the definition of a virtual device: "A software or hardware entity that responds to commands in a manner indistinguishable from the real device." Mother was telling me that the Tooth Fairy is a virtual person (simulated by loving parents) who responds to requests from children in a manner indistinguishable from the real fairy.

Mother also taught the IF ... THEN ... ELSE structure: "If it's snowing, then put your boots on before you go to school; otherwise just wear your shoes."

Mother explained the difference between batch and transaction processing: "We'll wash the white clothes when we get enough of them to make a load, but we'll wash these socks out right now by hand because you'll need them this afternoon."

Mother taught me about linked lists. Once, for a birthday party, she laid out a treasure hunt of ten hidden clues, with each clue telling where to find the next one, and the last one leading to the treasure. She then gave us the first clue.

Mother understood about parity errors. When she counted socks after doing the laundry, she expected to find an even number and groaned when only one sock of a pair emerged from the washing machine. Later she applied the principles of redundancy engineering to this problem by buying our socks three identical pairs at a time. This greatly increased the odds of being able to come up with at least one matching pair.

Mother had all of us children write our Christmas thank you notes to Grandmother, one after another, on a single large sheet of paper which was then mailed in a single envelope with a single stamp. This was obviously an instance of blocking records in order to save money by reducing the number of physical I/O operations.

Mother used flags to help her manage the housework. Whenever she turned on the stove, she put a potholder on top of her purse to reminder herself to turn it off again before leaving the house.

Mother knew about devices that raise an interrupt signal to be serviced when they have completed any operation. She had a whistling teakettle.

Mother understood about LIFO ordering. In my lunch bag she put the dessert on the bottom, the sandwich in the middle, and the napkin on top so that things would come out in the right order at lunchtime.

There is an old story that God knew He couldn't be physically present everywhere at once, to show His love for His people, and so He created mothers. That is the difference between centralized and distributed processing. As any kid who's ever misbehaved at a neighbor's house finds out, all the mothers in the neighborhood talk to each other. That's a local area network of distributed processors that can't be beat.

Mom, you were the best computer teacher I ever had.