10REM Random access file handling execisor
   20 
   21ON ERROR REPORT:CLOSE#0:END
   30file$="FRED"
   40len%=1024*128   : REM file size
   50blk%=514
   60 
   70max%=len%-blk%  : REM calc. max starting position in the file
   80 
   90@%=1:CLOSE#0
  100X%=OPENUP(file$)
  110REPEAT
  120P%=RND(max%)
  130Z%=RND(blk%)
  140B%=RND(256)
  150PRINT"Writing "Z%" bytes of "B%" at offset "P%
  160PTR#X%=P%
  170FORA%=1TOZ%
  180BPUT#X%,B%
  190NEXT
  200UNTIL0