Internal operating system usage. Does not return to caller. Applications use OS_Bye to kill itself.
DC_Bye returns to latest process or Index if none.
OS_Poll, poll for an application
DC_Pol, poll for card usage
OS_Stk, stack the current process (application)
OS_Ent, enter an application
DC_Ent, enter process
DC_Nam, name current application
OS_Exit, exit an application
OS_Bye, exit application
OS_Use, process card usage
DC_Alt, pass an alternative character