10	SUB MASETDR	! enable mailbox ast			&
			! unsolicited read attention		&

20	! Ruth E. Reebel					&
	! Copyright (c) 1982 by					&
	!	Amherst Associates Incorporated			&
	!	210 Old Farm Road				&
	!	Amherst, Massachusetts  01002			&

120	EXTERNAL LONG FUNCTION SYS$QIOW				&
\	EXTERNAL LONG IO$_SETMODE,IO$M_READATTN,MADRAST		&
\	DECLARE LONG FUNMOD,SYS_STATUS				&
\	FUNMOD=LOC(IO$_SETMODE) OR LOC(IO$M_READATTN)		&

130	COMMON (A1) MBX.CH%,LOG.CH%,TTY.CH%,CTL.FLG%,BAS.FOR%	&
\	MAP (RPH) READSET%	&

1000	SYS_STATUS=SYS$QIOW(,MBX.CH% BY VALUE,FUNMOD BY VALUE, &
		,,,MADRAST,,,,,)	&
\	CALL SYS$EXIT(SYS_STATUS BY VALUE) IF (SYS_STATUS AND 1%)=0%	&
!	if detached process tries to read MB, processing goes to MADRAST &
\	READSET% = -1%	! tell root that this has been done at least once &
			! so we won't try to reset it on CTRLC	&

32767	SUBEND