The HD44780 is the primary chip for a 16 character x 2 or 20 x 4 line LCD display.
These small displays can be found cheap online and are easy to use with a device with an I2C bus master.
You will find this on the Raspberry Pi and the Arduino Micro Controllers.
The display uses 7 inputs on the board to interface with the controller, but to make it I2C compatible, a PCF8574 is required.
This also gives us the ability to use the list output on the PCF8574 to control the LED backlight.
To help us use this dispaly, Moz4r created a service giving us a simple way to drive it from out code.
Pre-requits for this service is a device with an I2C Master and the PCF8574 service.