What is the output format of PINxn on atmega328p I have written this simple code to run on my Arduino:

#ifndef F_CPU
#define F_CPU 16000000UL // 16 MHz clock speed
#endif

#include &lt;avr/io.h&gt;
#include &lt;util/delay.h&gt;

int main(void)
{
  Serial.begin(9600);
  DDRD = 0x00;
  PORTD = 0x80; //activate pull-up resistor on first pin on port D

  while (1)
  {
    Serial.print(PIND);
  }
  return 0;
}


I simply set my D port as an input and read the value in a loop. The output of PIND is 253. What is this number representing? is it in decimals? where can I see a list of these? How can I see a binary repression of the PIN output (8 bits of them). I don not want to use bit shifting.
Serial.print(PIND, BIN); will write the value in PIND to the serial port in Base-2 representation.