printf problem plz help

i m using c51 microvision4....i have a simple program using logical bitwise operator .here is d part of d code...

#include <stdio.h>
void Display_Byte(const unsigned char);
int main()
{ unsigned char x = 0xFE;
unsigned int y = 0x0A0B;
printf("%-35s","x");
Display_Byte(x >>= 4);
return 0;
}

void Display_Byte(const unsigned char CH)
{ unsigned char i, c = CH;
unsigned char Mask = 1 << 7;
for (i = 1; i <= 8; i++)
{ putchar(c & Mask ? '1' : '0');
c <<= 1;
} putchar('\n');
}

bt while running this code icons like step one line,step over current line gets deactivated..and program doesnt work.it stays dr only..same happens for other program where i used printf and if it works where i will get to see output?