In [1]:
byte b1 = (byte)0b10000001;
byte b2 = (byte)0b00000001;

b1 + b2
|  Added variable b1 of type byte with initial value -127

|  Added variable b2 of type byte with initial value 1


|  Expression value is: -126
|    assigned to temporary variable $3 of type int

Out[1]:
-126