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
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.