(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). Various SOTS boxes provided necessities such as memory, hard drive controllers, and conventional expansion slots.
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Nearby terms: SLAM « SLANG « S-Lang « slap on the side » slash » slashdot effect » slave tty