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Definition: EMS

(1) (Electronic Message Service) The part of the radio spectrum assigned to electronic messaging over digital satellite circuits.

(2) (Electronics Manufacturing Services) A company that makes electronic devices for other companies. See contract manufacturer.

(3) (Enterprise Messaging Server) Original name for Microsoft's Exchange Server. See Microsoft Exchange.

(4) (Enhanced Message Service) An extension to the SMS short message service for cellphones that allows for the transmission of formatted text, icons, animations and ringtones. Introduced in the summer of 2001 by Alcatel, Ericsson, Motorola and Siemens, it allows up to 17 SMS messages to be strung together. See SMS and MMS.

(5) The plural of "em space." See em.

(6) (Expanded Memory Specification) The first technique that allowed DOS to reach beyond one megabyte, which was a big deal in those days. EMS provided access to 32MB by bank switching through a 64KB page frame in the upper memory area (see UMA). The application had to be written for EMS, such as Lotus 1-2-3 and AutoCAD, or was run with EMS-compliant system software such as DESQview. In IBM PC XTs and ATs, EMS required a board and driver, but 386 PCs could create EMS memory from extended memory. See DESQview.

EMS was confusing. Not only did expanded memory (EMS) and extended memory sound alike, but the user had to specify how much EMS was needed. Then Windows came out and managed all the RAM in the PC and allocated EMS automatically.