INTERRUPT CONTROL UNIT
8-2
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.
8.2
MASTER 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.
Figure 8-1. Interrupt Control Unit in Master Mode
8.2.1
Generic 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.
INT0 INT1 INT2 INT3
Interrupt
Priority
Resolver
Timer 0 Timer 1 Timer 2
DMA
0
DMA
1
Vector
Generation
Logic
To CPU Interrupt Request
F - Bus
A1506-A0
Summary of Contents for 80C186XL
Page 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Page 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Page 18: ...1 Introduction...
Page 19: ......
Page 27: ......
Page 28: ...2 Overview of the 80C186 Family Architecture...
Page 29: ......
Page 79: ......
Page 80: ...3 Bus Interface Unit...
Page 81: ......
Page 127: ......
Page 128: ...4 Peripheral Control Block...
Page 129: ......
Page 137: ......
Page 138: ...5 ClockGenerationand Power Management...
Page 139: ......
Page 154: ...6 Chip Select Unit...
Page 155: ......
Page 178: ...7 Refresh Control Unit...
Page 179: ......
Page 193: ......
Page 194: ...8 Interrupt Control Unit...
Page 195: ......
Page 227: ......
Page 228: ...9 Timer Counter Unit...
Page 229: ......
Page 253: ......
Page 254: ...10 Direct Memory Access Unit...
Page 255: ......
Page 283: ......
Page 284: ...11 Math Coprocessing...
Page 285: ......
Page 302: ...12 ONCE Mode...
Page 303: ......
Page 306: ...A 80C186 Instruction Set Additions and Extensions...
Page 307: ......
Page 318: ...B Input Synchronization...
Page 319: ......
Page 322: ...C Instruction Set Descriptions...
Page 323: ......
Page 371: ......
Page 372: ...D Instruction Set Opcodes and Clock Cycles...
Page 373: ......
Page 396: ...Index...
Page 397: ......