Emergency Management Services (EMS) provides an RS-232 accessible serial console interface to the bootloader menu on modern versions of Microsoft Windows.
During system installation of Windows Server 2003, EMS is enabled per default in case BIOS serial console redirection is supported and enabled beforehand. Otherwise, and in Windows XP, it is enabled with a command such as the following:
bootcfg /ems on /port com1 /baud 9600 /id 1
On Windows Vista it is enabled by typing the following command where {default} is the OS entry in BCDedit:
BCDedit /bootems {default} ON
In Windows Vista the serial port settings, Baud rate and Port ID, are accessed and modified using the following command:
BCDedit /emssettings EMSPORT:(port) EMSBAUDRATE:(rate)
On Windows Server 2003, this also starts a system console named Special Administration Console (SAC) during operating system run time providing headless server operation.