//---------------------------------------------------------------
// EXAMPLE EX20.C :  Demonstrate us of DOS KEYBOARD and DISPLAY
// Compile using: MCDOS ex20.c
// Then run TMP.EXE on a DOS machine!
//
// C.P. Diduch, Jan 2000.
//---------------------------------------------------------------
// Function definitions or prototypes.
char inportbdos(void); 
void outportbdos(char X);
//---------------------------------------------------------------
void main()
{
unsigned i;
char X;

i = 0;
while (i < 10) {
   X = 0x7F & inportbdos();
   outportbdos(X);
   i = i + 1;
   }
}
//---------------------------------------------------------------
char inportbdos(void) {
char X;
asm {
   push dx    ;	// Save register values.
   push ax    ;
   mov  ah, 8 ; // DOS Call to read a keypress.
   int  0x21  ; // ASCII value appears in register al.
   mov X, al  ;
   pop  ax    ; // Restore register values.
   pop  dx    ; 
   }
return X;
}
//---------------------------------------------------------------
void outportbdos(char X) {
asm {
   push dx    ;	// Save register values.
   push ax    ;
   mov  ah, 2 ; // DOS Call to read display ASCII value.
   mov  dl, X ; // ASII value is passed in register dl.
   int  0x21  ; // ASCII value appears in register dl.
   pop  ax    ; // Restore register values.
   pop  dx    ; 
   }
return;
}