#include <stdio.h>

/* Input a byte from a port */
inline unsigned char inportb(unsigned int port)
{
   unsigned char ret;
  
   asm volatile ("inb %%dx,%%al":"=a" (ret):"d" (port));
   return ret;
} 

/* Output a byte to a port */
/* July 6, 2001 added space between :: to make code compatible with gpp */
inline void outportb(unsigned int port,unsigned char value)
{
   asm volatile ("outb %%al,%%dx": :"d" (port), "a" (value));
} 

/* Stop Interrupts */
inline void stopints()
{
  asm ("cli");
}

unsigned char highmem, lowmem;
unsigned int mem;

int main()
{
/* need to stop ints before accessing the CMOS chip */
  stopints();

/* write to port 0x70 with the CMOS register we want to read */
/* 0x30 is the CMOS reg that hold the low byte of the mem count */
  outportb(0x70,0x30);

/* read CMOS values from port 0x71 */
  lowmem = inportb(0x71);

/* write to port 0x70 with the CMOS register we want to read */
/* 0x31 is the CMOS reg that hold the high byte of the mem count */
  outportb(0x70,0x31);

/* read CMOS values from port 0x71 */
  highmem = inportb(0x71);

/* fix the low and high bytes into one value */
  mem = highmem;
  mem = mem<<8;
  mem += lowmem;

  printf("\nOld style CMOS extended memory count is %uk.\n", mem);
}