Answer:
The embedded control program for the dental appliance is given below.
Machine Language Program
There are at least two sensible programs for the toothbrush. Here is one program:
| Address | Machine Instruction | Meaning |
|---|---|---|
| 0 | 0000 0001 | Rotate bristles left |
| 1 | 0000 0010 | Rotate bristles right |
| 2 | 0000 1000 | Skip next instruction if switch is off |
| 3 | 0000 0100 | Go back to start of program |
| 4 | 0000 0000 | Stop running |
In the electronic memory of the toothbrush the program is stored as a sequence of bits:
0000 0001 0000 0010 0000 1000 0000 0100 0000 0000
The processor starts at the beginning and performs the action described by each code. This is, of course, a silly 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.
QUESTION 5:
Will the electric toothbruch stop immediately when the switch is turned off? (Follow through the program to see if this happens.)