In computer science, the sign bit is a bit in a signed number representation that indicates the sign of a number. Although only signed numeric data types have a sign bit, it is invariably located in the most significant bit position, so the term may be used interchangeably with 'most significant bit' in some contexts.
Almost always, if the sign bit is 0, the number is non-negative (positive or zero). If the sign bit is 1 then the number is negative, although formats other than two's complement integers allow a signed zero: distinct 'positive zero' and 'negative zero' representations, the latter of which does not correspond to the mathematical concept of a negative number.
In the two's complement representation, the sign bit has the weight −2w−1 where w is the number of bits. In the ones' complement representation, the most negative value is 1 − 2w−1. In a sign-and-magnitude representation of numbers, the value of the sign bit determines whether the numerical value of the other bits is negated.
Floating point numbers, such as IEEE format, IBM format, VAX format, and even the format used by the Zuse Z1 and Z3 use a sign-magnitude representation.
In the two's complement representation, the sign bit has the weight −2w−1 where w is the number of bits. In the ones' complement representation, the most negative value is 1 − 2w−1, but there are two representations of zero, one for each value of the sign bit. In a sign-and-magnitude representation of numbers, the value of the sign bit determines whether the numerical value is positive or negative.
When using a complement representation, to convert a signed number to a wider format the additional bits must be filled with copies of the sign bit in order to preserve its numerical value, a process called sign extension or sign propagation.
After starting life in 2014 as a series of parties run by Lukas Werner Mehling and Kilian Krings, Sign Bit Zero expanded into an accompanying record label in 2016, kicking things off with a pair of edits by Mick Wills. The collective’s main focus is on reissues and edits as well as new productions experimenting with a sound which encompasses New Wave/NDW; Obscure Electronics; Industrial; and EBM. Graphics by Lukas Werner Mehling; Musical Direction by Kilian Krings.