HD44780 issues

I reckon something's wrong with your wiring, because pin A11 isn't even on a pin header :) http://www.espruino.com/ReferenceESPRUINOBOARD

You should be able to use any pins though - although try not to use the 3 that are also used for the LEDs.

The block of pixels happens when the display powers on - so it could be anything (but at least you know the display is working).

I just tried again here, and it still works fine (and I tried on a few different sets of pins). I'll update the docs, but these are the connections/code I'm using:

//                                   rs,en,d4,d5,d6,d7
var lcd = require("HD44780").connect(A0,A1,C0,C1,C2,C3);
lcd.print("Hello World!");