void setup() {
  // put your setup code here, to run once:
 Serial.begin(9600);
  int data1 = 0x1234; //data are saved in decreasing RAM memory locations
  int data2 = 0xABCD;
  Serial.println(data2);
  Serial.println((unsigned int)&data2,HEX);

  int *ptr; //pointer variable ptr holds address of a word-wide location

  ptr = &data1; //ptr holds address of data1
  Serial.println((unsigned int)ptr, HEX); //shows: address of data1: 08FA
  int rdData1 = *ptr;
  Serial.println((unsigned int)rdData1, HEX);  //shows: 1234
  Serial.println();

  ptr--;//ptr = &data2; //ptr holds address of data2
  Serial.println((unsigned int)ptr, HEX); //shows:address of data2: 08F8
  int rdData2 = *ptr;
  Serial.println(rdData2, HEX);  //does not show: ABCD
  Serial.println();
}

void loop() {
  // put your main code here, to run repeatedly:

}