#define letter_width 14
#define letter_height 10
static unsigned char letter_bits[] = {
   0xff, 0x3f, 0x07, 0x38, 0x09, 0x24, 0x11, 0x22, 0xe1, 0x21, 0xd1, 0x22,
   0x09, 0x24, 0x05, 0x28, 0x03, 0x30, 0xff, 0x3f};