anchor.diff:  # house keeping functions
   help
   run 10ns
  +run 20ns
   pause
   call debug_prompt
   history
   repeat 1
   history clear
   history
  -history clear
   
   # register access
   rd_addr 0
  +rd_addr 4 
  +
  +# load command file
  +history save demo1
  +read demo1
  +
  +wr_addr 4 1
  +rd_addr 4 
   rd_reg regmodel.IntMask 
   wr_reg regmodel.IntMask 0
   rd_reg regmodel.IntMask 
  
positive.code: # start a new sequence
  seq_create vip_my01_seq my01_seq
  seq_rand my01_seq
  
  run 20000ns
  
  seq_start -priority 200 -new_thread 1 my01_seq env.vip.sqr
  
  run 20000ns
  
negative.code: 
  # send a sequence item
  seq_item_create vip_tr tr
  seq_item_set_fields tr chr='hff
  seqr_execute_item env.vip.sqr tr
  
  