函数名: enable 
 功  能: 开放硬件中断 
 用  法: #include <dos.h> 
         void enable(void); 
 程序例: 
/* ** NOTE: 
 This is an interrupt service routine. You can NOT compile this program 
 with Test Stack Overflow turned on and get an executable file which will 
 operate correctly. 
 */ 
#include <stdio.h> 
 #include <dos.h> 
 #include <conio.h> 
/* The clock tick interrupt */ 
 #define INTR 0X1C 
void interrupt ( *oldhandler)(void);
int count=0;
void interrupt handler(void) 
 { 
 /* 
    disable interrupts during the handling of the interrupt 
 */ 
    disable(); 
 /* increase the global counter */ 
    count++; 
 /* 
    re enable interrupts at the end of the handler 
 */ 
    enable(); 
 /* call the old routine */ 
    oldhandler(); 
 } 
int main(void) 
 { 
 /* save the old interrupt vector */ 
    oldhandler = getvect(INTR); 
/* install the new interrupt handler */ 
    setvect(INTR, handler); 
/* loop until the counter exceeds 20 */ 
    while (count < 20) 
       printf("count is %d\n",count); 
/* reset the old interrupt handler */ 
    setvect(INTR, oldhandler); 
   return 0; 
 }