cmp     r2,$core / at beginning of user program yet?
       blos    2f / yes, return
       cmp     r2,u.usp / is break_above the "stack pointer before
                        / swapping"
       bhis    2f / yes, return
       mov     $ecore,r3 / r3 points to end of core
       add     r3,r2
       sub     u.usp,r2 / end of users stack is in r2
1:
       mov     -(r2),-(r3) / move stack back to its normal place
       cmp     r2,u.break / in core
       bne     1b
2:
       rts     r0

putlu: / r1 = user process no.; r2 points to lowest priority queue
       tstb    (r2)+ / is queue empty?
       beq     1f / yes, branch
       movb    (r2),r3 / no, save the "last user" process number in r3
       movb    r1,p.link-1(r3) / put pointer to user on "last users" link
       br      2f /
1:
       movb    r1,-1(r2) / user is only user; put process no. at beginning
                         / and at end
2: 
       movb    r1,(r2) / user process in r1 is now the last entry on
                       / the queue
       dec     r2 / restore r2
       rts     r0

copyz:
       mov     r1,-(sp) / put r1 on stack
       mov     r2,-(sp) / put r2 on stack
       mov     (r0)+,r1
       mov     (r0)+,r2
1:
       clr     (r1)+ / clear all locations between r1 and r2
       cmp     r1,r2 
       blo     1b
       mov     (sp)+,r2 / restore r2
       mov     (sp)+,r1 / restore r1
       rts     r0 

idle:
       mov	*$ps,-(sp) / save ps on stack
       clr	*$ps / clear ps
       mov	clockp,-(sp) / save clockp on stack
       mov	(r0)+,clockp / arg to idle in clockp
       1 / wait for interrupt
       mov      (sp)+,clockp / restore clockp, ps
       mov	(sp)+,*$ps
       rts	r0

clear:
       jsr       r0,wslot / get an I/O buffer set bits 9 and 15 in first
                          / word of I/O queue r5 points to first data word