One Number in Hex, Decimal, Binary and Octal at Once RADIX
The programmer-mode calculator you keep open: one number in hex, decimal, binary and octal at once, a grid of bits you can click, and the bitwise operations — with the width and sign that decide what the bits mean.
The number
Bitwise and arithmetic
The operation applies the operand to the current number, at the chosen width. NOT ignores the operand.
Width and sign are the whole point
The same bits are a different number depending on how wide the register is and whether it is signed: 0xFF is 255 or −1, a right shift fills with zeros or the sign bit, an add wraps at the width. RADIX shows all of it at once and computes exactly in two's-complement to 64 bits, so you read the answer instead of deriving it.