slack = S = slash

slap on the side n.

(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 `PCjr'). Various SOTS boxes provided necessities such as memory, hard drive controllers, and conventional expansion slots.

--The Jargon File version 4.3.1, ed. ESR, this entry manually entered by rootbeer277.