floresta:
The display starts up in 4-bit mode. It uses 4 wires to communicate.
No and yes. The device actually starts up in 8-bit mode. Since it may actually be hooked up in a 4-bit system the first few instructions in the initialization sequence, the ones that are used to switch it out of the 8-bit mode if that is necessary, only require the use the of the upper four bits - the lower four bits are ignored even if they are hooked up.
Thanks for pointing that out. I did read the spec sheet a while back and that was in it.