(AlSo called a Sidecar, or abbreviated "SOTS"). A type of external expanSion hardware marketed by computer manufacturerS (e.g. Commodore for the Amiga 500/1000 SerieS and IBM for the hideouS failure called IBM PCjr). VariouSSOTS boxeS provided neceSSitieSSuch aS memory, hard drive controllerS, and conventional expanSion SlotS. [Jargon File]