Intel 80C186XL, 80C188XL user manual 8.2MASTER MODE, 8.2.1Generic Functions in Master Mode

Models: 80C186XL 80C188XL

1 405
Download 405 pages 42.62 Kb
Page 197
Image 197
8.2MASTER MODE

INTERRUPT CONTROL UNIT

Interrupts eliminate the need for polling by signalling the CPU that a peripheral device requires servicing. The CPU then stops executing the main task, saves its state and transfers execution to the peripheral-servicing code (the interrupt handler). At the end of the interrupt handler, the CPU’s original state is restored and execution continues at the point of interruption in the main task.

8.2MASTER MODE

Figure 8-1 shows a block diagram of the Interrupt Control Unit in Master mode. In this mode, the ICU processes all interrupt requests, both external and internal. The three timer interrupt requests share a single input, while the others are supported directly.

 

DMA

DMA

 

Timer 0 Timer 1 Timer 2

0

1

INT0 INT1 INT2 INT3

 

Interrupt

 

 

Priority

 

 

Resolver

 

 

 

 

Vector

To CPU Interrupt Request

 

 

Generation

 

 

 

Logic

 

F - Bus

 

 

 

 

A1506-A0

Figure 8-1. Interrupt Control Unit in Master Mode

8.2.1Generic Functions in Master Mode

Several functions of the Interrupt Control Unit are common among most interrupt controllers. This section describes how those generic functions are implemented in the Interrupt Control Unit.

8-2

Page 197
Image 197
Intel 80C186XL, 80C188XL user manual 8.2MASTER MODE, 8.2.1Generic Functions in Master Mode