Example 81. initializing the interrupt control un – Intel 80C188XL User Manual

Page 226

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8-31

INTERRUPT CONTROL UNIT

5.

Set the mask bit in the Interrupt Mask register for any interrupts that you wish to disable.

Example 8-1 shows sample code to initialize the Interrupt Control Unit.

Example 8-1. Initializing the Interrupt Control Unit for Master Mode

$mod186

name

example_80C186_ICU_initialization

;

;This routine configures the interrupt controller to provide two cascaded

;interrupt inputs (through an external 8259A connected to INT0 and INTA0#)

;and two direct interrupt inputs connected to INT1 and INT3. The default

;priorities are used.

;

;The example assumes that the register addresses have been properly defined.

;

code

segment

assume cs:code

set_int_

proc near

push dx

push ax

mov

ax,0110111B

;cascade mode, priority seven

mov

dx,I0CON

;INT0 control register

out

dx,ax

mov

ax,01001101B

;unmask INT1 and INT3

mov

dx,IMASK

out

dx,ax

pop

ax

pop

dx

ret

set_int_

endp

code

ends

end

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