bne	3f / no
	asr	r2 / yes, it is a parent
	cmpb	p.stat-1(r2),$3 / is the child of this dying process a
		                / zombie
	bne	2f / no
	clrb	p.stat-1(r2) / yes, free the child process
2:
	asl	r2
3: / search the process name table for the dying process's parent
	cmp	p.pid-2(r2),r4 / found it?
	bne	3f / no
	mov	r2,r5 / yes, put index to p.pid table (parents
		      / process # x2) in r5
3:
	cmp	r2,$nproc+nproc / has whole table been searched?
	blt	1b / no, go back
	mov	r5,r1 / yes, r1 now has parents process # x2
	beq	2f / no parent has been found. The process just dies
	asr	r1 / set up index to p.stat
	movb	p.stat-1(r1),r2 / move status of parent to r2
	beq	2f / if its been freed, 2f
	cmp	r2,$3 / is parent a zombie?
	beq	2f / yes, 2f
	movb	u.uno,r3 / move dying process's number to r3
	movb	$3,p.stat-1(r3) / make the process a zombie
	cmp	r2,$2 / is the parent waiting for this child to die
	bne	2f / yes, notify parent not to wait any more
	decb	p.stat-1(r1) / awaken it by putting it (parent)
	mov	$runq+4,r2 / on the runq
	jsr	r0, putlu
2: / the process dies
	clrb	u.uno / put zero as the process number, so "swap" will
	jsr	r0,swap / overwrite process with another process
	0	/ and thereby kill it; halt?

intract: / interrupt action
	cmp	*(sp),$rti / are you in a clock interrupt?
	bne	1f / no, 1f
	cmp	(sp)+,(sp)+ / pop clock pointer
1: / now in user area
	mov	r1,-(sp) / save r1
	mov	u.ttyp,r1 / pointer to tty buffer in control-to r1
	cmpb	6(r1),$177 / is the interrupt char equal to "del"
	beq	1f / yes, 1f
	clrb	6(r1) / no, clear the byte (must be a quit character)
	mov	(sp)+,r1 / restore r1
	clr	u.quit / clear quit flag
	bis	$20,2(sp) / set trace for quit (sets t bit of ps-trace trap)
	rti	          / return from interrupt
1: / interrupt char = del
	clrb	6(r1) / clear the interrupt byte in the buffer
	mov	(sp)+,r1 / restore r1
	cmp	u.intr,$core / should control be transferred to loc core?
	blo	1f
	jmp	*u.intr / user to do rti yes, transfer to loc core
1: