> It has been plausibly suggested that "foobar" spread among early computer engineers partly because of FUBAR and partly because "foo bar" parses in electronics

> It has been plausibly suggested that "foobar" spread among early computer engineers partly because of FUBAR and partly because "foo bar" parses in electronics techspeak as an inverted foo signal. Can anyone educate me what "inverted foo signal" means here, in connection to electronics?