A keyboard which has its natural keys colored black, and its accidentals (sharps/flats) colored white. This is done strictly for aesthetics, or as an attention-getter. Many combo organs of the 1960s had reverse keys over part or all of the keyboard, and Farfisa also used gray keys. More recently, Korg occasionally does special issues of some of its synths with reverse keys, most recently the Microkorg. The Hammond organ used reverse keys for a special purpose: it indicated a part of the keyboard which did not play notes, but rather was connected to patch selecting switches.