IntCalc for

From Inertron Software:

IntCalc is a calculator with a clean, simple interface. You can use it in either "normal" algebraic mode (using the equal sign) or RPN mode (using the Enter button); it is easily switchable between the two modes at any time. Features include: One tap toggling between integer and floating point modes; integers displayable in any of binary, octal, decimal, hexadecimal, or ASCII; integer bit shifts, rotates, bitwise AND, OR, etc.; floating point square root, reciprocal.