Sign/magnitude ADCs almost have signed zero in hardware, by generating a sign bit and zero or more magnitude bits. The typical method to map to voltages double

Sign/magnitude ADCs almost have signed zero in hardware, by generating a sign bit and zero or more magnitude bits. The typical method to map to voltages doubles the span between adjacent values and skips over zero. So a 2-bit sign/magnitude ADC measures values in the series {-3, -1, 1, 3}. So strictly speaking this number system doesn't have a representation of zero at all. Tiny measurements either round up or round down to +/- 1.