void setup() {
  Serial.begin(115200);
  byte start = 0b10101011;
  byte mask = 0b11110000;
  byte result = start & ~mask;

  printBinWithLeading(start);
  Serial.print("\tstart\n");

  printBinWithLeading(~mask);
  Serial.print(  "\tand'ed with ~mask (");

  printBinWithLeading(mask);
  Serial.println(")");

  printBinWithLeading(result);
  Serial.println("\tyields");
}

void loop() {
}

void printBinWithLeading(byte funcResult) {
  // byte funcRresult;
  for (int i = 7; i >= 0; i--) {
    //  Serial.println(i);
    if (bitRead(funcResult, i)) {
      Serial.print("1");
    }
    else {
      Serial.print("0");
    }
  }

}