anchor.diff:  -define(STOREB,    [reset,{fetchp,{t,16#1d5}},{bstore,{b,16#1d5}},{fetchp,{t,678}},nop,{storeb,{b,16#1d5},{t,678}}]).
   -define(READ,      [reset,{fetchp,{t,16#1d5}},{bstore,{b,16#1d5}},{fetchb,{t,678}},nop]).
   
  --define(READX,     [reset,read,{read,678},eof]).
   -define(WRITE,     [reset,{write,678},{write,ok},eof]).
   -define(READ_STOP, [reset,nop,read,stop]).
   -define(WRITE_STOP,[reset,nop,{write,123},stop]).
  
positive.code:    M = setup("-- READ TEST/STEP"),
     util:unregister(n000),
  
     F18A = f18A:create(n001,n000,[read]),
  
     f18A:reset(F18A),
  
     spawn(fun() ->
              f18A:step (F18A,wait),
              f18A:step (F18A,wait),
              M ! { n001,stopped }
  
negative.code:                        end)),
     
     check(waitall([{n000,stopped},{n001,stopped}]),
           [ { ?READ,n001 }
           ]).
  
  write_go_test() ->
  