Computer Interfacing

3 Conversion between

digital and analogue

We saw in the last chapter that signals generated in the

real world to represent the quantities that we wish to

measure and control are usually quite different from

those that the computer requires. In short, they are ana-

logue signals whereas the computer requires a digital

input. In order to make the computer accept data that

represents the input quantity, the analogue signal has

to be converted into the appropriate digital form, for

example,

8-bit

binary. Similarly the only type of signal

that the computer is able to generate directly for con-

trol purposes is a digital one. If the control device