//---------------------------------------------------------------
// L311.C
// Wait for a positive edge at bit-0 of input port 0x13A.
//
// C Code for the SBC188 Board.
// C.P. Diduch, Dec 1999.
//---------------------------------------------------------------
#define	KEY_PA 	0x138	  // 82C55A port addresses for PA,
#define KEY_PB 	0x13A	  // PB,
#define KEY_PC 	0x13C	  // PC and the
#define KEY_CON	0x13E	  // Control Register.

#include <conio.h> 	  // conio.h contains prototypes for 
			  // inportb() and outportb(). 
//---------------------------------------------------------------
void main()
{
unsigned char X, Y;

outportb(KEY_CON, 0x82);  // Initialize KEY_PC and KEY_PA
			  // as OP ports and KEY_PB as an
				// IP port.

while( (X = 0x01 & inportb(KEY_PB)) == 0) {}
while( (Y = 0x01 & inportb(KEY_PB)) != 0) {}
}