v7 man page for alarm

ALARM(2)							System Calls Manual							  ALARM(2)

NAME
       alarm - schedule signal after specified time

SYNOPSIS
       alarm(seconds)
       unsigned seconds;

DESCRIPTION
       Alarm causes signal SIGALRM, see signal(2), to be sent to the invoking process in a number of seconds given by the argument.  Unless caught
       or ignored, the signal terminates the process.

       Alarm requests are not stacked; successive calls reset the alarm clock.	If the argument is 0, any alarm request is cancelled.  Because the
       clock has a 1-second resolution, the signal may occur up to one second early; because of scheduling delays, resumption of execution of when
       the signal is caught may be delayed an arbitrary amount.  The longest specifiable delay time is 65535 seconds.

       The return value is the amount of time previously remaining in the alarm clock.

SEE ALSO
       pause(2), signal(2), sleep(3)

ASSEMBLER
       (alarm = 27.)
       (seconds in r0)
       sys alarm
       (previous amount in r0)

																	  ALARM(2)