Emergency Management Services (EMS) provides an RS-232 accessible serial console interface to the bootloader menu on modern versions of Microsoft Windows.
Otherwise, and in Windows XP, it is enabled with a command such as the following: On Windows Vista it is enabled by typing the following command where {default} is the OS entry in BCDedit: In Windows Vista the serial port settings, Baud rate and Port ID, are accessed and modified using the following command: On Windows Server 2003 and later, this also starts a system console named Special Administration Console (SAC) during operating system run time providing headless server operation.
An administrator can use SAC to access a command prompt, shutdown or reboot the machine, collect a crash dump, or view system information such as the hostname, OS version, running processes, or an IP address or addresses.
To list all the channels that SAC has open from the top-level prompt, the user needs to enter the ch command.
This makes it easy for a program that is watching SAC output to detect when certain events occur.