Machine Language Program

There are at least two sensible programs for the toothbrush. Here is one of them:

Address	Machine Instruction
0	0000 0001
1	0000 0010
2	0000 1000
3	0000 0100
4	0000 0000

To help you read the program, here is the list of machine operations:

Machine Instruction	Machine Operation
0000 0000	Stop
0000 0001	Rotate bristles left
0000 0010	Rotate bristles right
0000 0100	Go back to start of program
0000 1000	Skip next instruction if switch is off

This is, of course, a stupid example. Electric toothbrushes are not controlled by computer processors. And, the machine instructions of actual processors are much more detailed. But the essential ideas of the example are these:

• A machine language program is a sequence of machine language instructions in main memory.
• A machine instruction consists of one or more bytes (in the example, only one.)
• The processor runs a program one machine instruction at a time.
• All the little machine operations add up to something useful.

If toothbrush user leaves the switch "on" for a while, the program repeats its operations many times. This is how most programs in real computers run--many little operations add up to a useful function, which is then repeated many times.