Hi everyone :) I was wondering what are the rest of the pins in the LCD header that are not used but the NerdKit guide? Is there anyway I can find what pins match HD44780's datasheet?

Four of them are used for 8-bit data transfer mode, and one is used to read the status and character address. Wikipedia

Oh! So stuff like busy flag can actually be read as a data! I kept thinking one of the unused pins will be 0 when free and 1 when busy. Nevermind, thanks :)

During one of my Internet searches for something, I did happen across this PDF. This seems to be the same LCD that's used in the kit. Has some pinouts, dimensions, etc. Hopefully someone find this useful :)