"Original Chip Set" is the first graphics chipset to come with the Amiga computers. OCS was used primarily from 1985 to 1992 and available on the Amiga 1000, 500 and 2000. It offers the most limited resolutions of the three available chipsets. It could display up to 32 standard colors, 64 EHB colors, or 4096 colors using HAM mode. It was later improved upon by ECS and then AGA.

In military circles, Officer Candidate School.  Currently, in the US Army, in order to be eligible for OCS, the aspirant must have 90 semester hours, at least a 850 on the SAT or 19 on the ACT, and--of course--must meet Army standards for PT and marksmanship.  In addition, the candidate must receive a bachelor's degree (in any subject) within two and a half years of graduating from OCS.

In linguistic and ecclesiastical circles, Old Church Slavonic.  It is the liturgical language of the Russian Orthodox Church.  As the name suggests, it is a Slavic language, related to Russian, Ukrainian, and Byelorussian.