Fairly certain the displays are written in here:
Where do I control the DIMM Pin?
//converts num to the proper 7 segment value and writes to the home display
void displayNum(int num)
{
int digit1 = seg_codes[num%10];
int digit10 = seg_codes[num/10];
shiftOut(dataPin, clockPin, LSBFIRST, digit1);
shiftOut(dataPin, clockPin, LSBFIRST, digit10);
}
//converts num to the proper 7 segment value and writes to the visitor display
void VdisplayNum(int Vnum)
{
int digit1 = seg_codes[Vnum%10];
int digit10 = seg_codes[Vnum/10];
shiftOut(VdataPin, VclockPin, LSBFIRST, digit1);
shiftOut(VdataPin, VclockPin, LSBFIRST, digit10);
}