Big Picture 2: Computers and Programs

Q: Well what about computers? What are they, and how do computer scientists use them?

A: A computer is a machine that manipulates symbols.

Q: What is a symbol?

A: Any discrete entity can be thought of as a symbol. Common symbols are letters, numbers, punctuation marks, and strings of characters.

One important implication of this is that computers can be used to manipulate anything that can be represented symbolically.

Q: How does the computer manipulate the symbols?

A: According to rules.

Q: What rules?

A: The rules you—the programmer—specify.

Q: How do I do that?

A: First you find/develop a computational procedure that solves the problem at hand. (This is known as an algorithm).

Next you write that procedure as a computer program.

Then you load it into the computer.

Finally you run/execute the program enabling it take control of the computer and its resources, and admire your handiwork.

Q: Great. But what's a program?

A: A list of instructions telling the computer what to do.