Turbo / Borland C specific: console snippit

In case someone is interested; here's a bit of code to move about a cursor within a viewport. Dunno how many bugs there are, but feel free to point any out.

Code:

/* Compiled using BC 5; MSDOS app

   dos based apps are dodgy in
   windows; not recommended on
   XP, Vista, Win7.  Try dosbox
   instead
*/

#include <conio.h>

#define UP 72  /* up arrow    */
#define LF 75  /* left arrow  */
#define RT 77  /* right arrow */
#define DN 80  /* down arrow  */

#define VP_UL  201  /* upper left      */
#define VP_LL  200  /* lower left      */
#define VP_UR  187  /* upper right     */
#define VP_LR  188  /* lower right     */
#define VP_VL  186  /* vertical line   */
#define VP_HL  205  /* horizontal line */


/* to change the viewport size, modify below */

#define VP_X_MIN 13 /* minimum value of cx */
#define VP_X_MAX 65 /* maximum value of cx */
#define VP_Y_MIN  5 /* minimum value of cy */
#define VP_Y_MAX 20 /* maximum value of cy */

/*
   cprintf is needed if changing of
   foreground and background colors
   is desired

   textbackground(0-7)
   textcolor(0-14)
*/

void drawViewport(void);

int main(void) {

   int cx = 39, cy = 12, scan1, scan2;
   unsigned char mc = 234;

   _setcursortype(_NOCURSOR);
   drawViewport();
   gotoxy(cx, cy);
   cprintf("%c", mc);

   for(; (scan1 = getch()) != 13; ) {
      if(scan1 == 0) {

         scan2 = getch();
         gotoxy(cx, cy);
         putch(' ');

         cx = (scan2 == LF && cx == VP_X_MIN ? VP_X_MAX :
               scan2 == LF && cx - 1 >= VP_X_MIN ? --cx  :
               scan2 == RT && cx == VP_X_MAX ? VP_X_MIN :
               scan2 == RT && cx + 1 <= VP_X_MAX ? ++cx  : cx);

         cy = (scan2 == UP && cy == VP_Y_MIN ? VP_Y_MAX :
               scan2 == UP && cy - 1 >= VP_Y_MIN ? --cy  :
               scan2 == DN && cy == VP_Y_MAX ? VP_Y_MIN :
               scan2 == DN && cy + 1 <= VP_Y_MAX ? ++cy  : cy);

         gotoxy(cx, cy);
         cprintf("%c", mc);
      }
   }

   _setcursortype(_NORMALCURSOR);

   return 0;
}

void drawViewport(void) {

   int x1 = VP_X_MIN - 1,
       x2 = VP_X_MAX + 1,
       y1 = VP_Y_MIN - 1,
       y2 = VP_Y_MAX + 1;

   /* draw top and two end points of viewport */

   gotoxy(x1, y1); cprintf("%c", VP_UL);

   for(x1 = VP_X_MIN; x1 < x2; ++x1) {
      gotoxy(x1, y1); cprintf("%c", VP_HL);
   }

   gotoxy(x2, y1); cprintf("%c", VP_UR);

   /* draw left and right sides */

   x1 = VP_X_MIN - 1;
   y1 += 1;

   for(; y1 < y2; ++y1) {
      gotoxy(x1, y1); cprintf("%c", VP_VL);
      gotoxy(x2, y1); cprintf("%c", VP_VL);
   }

   /* draw bottom and two end points */

   gotoxy(x1, y2); cprintf("%c", VP_LL);

   for(x1 = VP_X_MIN; x1 < x2; ++x1) {
      gotoxy(x1, y2); cprintf("%c", VP_HL);
   }

   gotoxy(x2, y2); cprintf("%c", VP_LR);
}