.PS
log_init
S: NOR_gate
  left_
R: NOR_gate at S+(0,-L_unit*9)
  line right_ L_unit*3 from S.Out ; line to (Here,R.In2) then to R.In2
  line left_ L_unit*3 from R.Out ; line to (Here,S.In2) then to S.In2
  line left_ 4*L_unit from S.In1 ; "$S$sp_" rjust
  line right_ 4*L_unit from R.In1 ; "sp_$R$" ljust
.PE