code/modules/networks/computer3/mainframe2/_base_os.dm

/datum/computer/file/mainframe_program/os/kernel	The kernel is the computer program at the core of the OS and is responsible for managing interactions with all hardware devices, such as terminals, databanks, scanners and so forth through device drivers; for handling inputs; for creating and terminating connections; for the execution of system calls; and for other basic system services.
/datum/computer/file/mainframe_program/login	The user login manager is responsible for passing user login credentials from the user to the kernel to be authenticated, displaying the daily welcome message to the user, and for notifying the user in the event of a login failure.