hi, i'm new to arduino.
I try to use a 4x20 hd4470 based lcd with arduino's lcd tutorial but it don't work
Display show #1 and #3 lines with all characters black and #2 and #4 lines empty characters.
some idea?
i''ve tried 8-bit tutorial and 4-bit tutorial, without solutions 
thx!
Some 4x20 displays have 2 hd4470 IC's to control them, maybe that is your problem ?
Not sure where but there is mod to the library to work with 4 lines. I'm still waiting for my 4 line to arrive.
This may be it:
I have the same problem.
Its not really a problem by its self actually.
It just means that your not talking to it correctly (its the default state). Once you have it working properly then the bars will go away and the extra lines will work perfectly.
No dont ask me why its not working. I dont have a clue.
If I did I'd have my LCD working and I'd be a happy man. 
Hi, sorry for my long time response, in italy there's holiday 
So...
I've tried to use this tutorial:
without using library.
It's works!
lcd library using 8bits maybe dosen't talk correct to lcd.
i will debug LCD libray code, download on site, ASAP!
stay tuned.
thx for replays!