(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) (Expanded Memory Specification) The first technique that allowed DOS to reach beyond one megabyte. It provided access to 32MB by bank switching through a 64KB page frame in the UMA. The application was either written for EMS (Lotus 1-2-3, AutoCAD, etc.) or was run with system software that supported it, such as DESQview. In XTs and ATs, EMS required a board and driver, but 386 PCs could create EMS memory from extended memory. See UMA and DESQview.
There was a lot of confusion over EMS. Not only did expanded memory (EMS) and extended memory sound alike, but you had to specify how much EMS you needed. When Windows came along, it managed all memory in the PC and allocated EMS automatically for old DOS applications that required it.
