$DEF RTIN = 16_0D, RTOUT = 16_11, NPRREQ = NPR.0
$DEF RINTST = 16_2E, TOPSEG = 16_E8, RDATA = 16_20, SSEL = 16_24
BRG=0
CSR2=BRG; CSR3=BRG; CSR4=BRG; CSR5=BRG
SP10=BRG; SP11=BRG; SP12=BRG; SP13=BRG
SP6=BRG;    ! LOW ORDER ADDRESS
SP5 = 16_C0;  ! TRANSFER TO ADDRESS 140000
ADR2=16_FF; ADR3=16_FF;  ! _SOURCE SELECT = -1
ADR6=SSEL; ADR7=TOPSEG
MISC=16_1C;  ! SET CLOCK & O ADR 17&18
NPR = RTOUT
CYCLE; REPEAT IF NPRREQ
SETREC:
ADR2=1; ADR3=0; ! SET RECEIVE=1
ADR6=RINTST
MISC = 16_0C
NPR=RTOUT
CYCLE; REPEAT IF NPRREQ
CYCLE
   MISC=16_10; ! CLOCK ON
   CYCLE; REPEAT IF MISC.4 = 0
     ADR4=RINTST
      ADR5=TOPSEG
   NPR = RTIN
   CYCLE; REPEAT IF NPRREQ
   ! GOT RING INTSTATUS - CHECK FOR PACKET RECD
   IF ADR1.7 = 0 
      JUMP NODATA
   FINISH
   ADR4=RDATA
   NPR = RTIN
   CYCLE; REPEAT IF NPRREQ
   ADR7 = SP5
   ADR6 = SP6
   ADR3=ADR1
   ADR2=ADR0
   MISC = 0;     ! NOT TOP BITS  (PROBLEMS OVER CLEARING ODDS&ENDS?
   NPR = RTOUT
   CYCLE; REPEAT IF NPRREQ; ! SEND DATA TO PDP11
   SP6 = SP6+1
   IF C
      SP5 = SP5+1
   FINISH
   SP10 = SP10+1
   IF C
      SP11 = SP11+1
      IF C
         SP12 = SP12+1
         IF C
            SP13 = SP13+1
         FINISH
      FINISH
   FINISH
   CSR2 = SP10
   CSR3=SP11; CSR4=SP12; CSR5=SP13
   JUMP SETREC
NODATA:
REPEAT