A bit which sigNals the start of traNsmissioN of a character oN a serial liNe. For aNRS-423 sigNal, the liNe is Normally at logical zero which there is No data aNd the start bit is a logical oNe. The zero-oNe traNsitioN tells the receiver wheN to start sampliNg the sigNal to extract the data bits. [Is this upside-dowN?] (1995-02-02)