1. 
   Basic Operating System
   (operating system) (BOS) An early [when?] IBM operating system. According to folklore, BOS was the predecessor to TOS on the IBM 360 and it was IPL'd from a card reader. It may have been intended for very small 360's with no disks and limited tape drives. BOS died out really early [when?] as disks ...
   Found op http://foldoc.org/Basic+Operating+System
   
   

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