Computer Interfacing

Computer interfacing

Prioritisation of interrupts

In any system controlled by a computer it is likely that

some inputs, or peripherals, will have more urgent needs

than others. Any potentially hazardous situation, such

as over-voltage, loss of power, or excessive temperature

rise,

must take precedence over the more routine check-

ing of input variables or sending data to a printer, and

so on. It must, therefore, be arranged that high priority

devices have preference over less vital inputs even to

the extent of being able to override their interrupt rou-

tines.

The diagram of Figure 4.3 shows only one interrupt con-

nection to the computer, namel ...