First, I did some little tests to get the pins of the stepper motors right ( I didnt find a datasheet on google ). I must add that I had never before worked with stepper motors and had no idea how to use them. Afer a little google search ( also about the darlington arrays and their function, I just heard that they were used to drive steppers ) I got them working and was drawing my first square on the drum plotter.

Functions for penUp and penDown were quickly programmed, and after a lot of further programming and googling ( I‘ve tought myself the arduino language so far ) I drew my first 8x8 bitmap image stored in a simple 2d byte array.

Using PROGMEM, I gradually increased that size up to 128x128 pixels, where the Arduino‘s storage was full. At that time, I was using an application I quickly wrote in Flash to get a png image to the arduino ( by copy-pasting the generated array definition into the arduino sketch ).

But I wanted to go bigger and easier and so I looked into Processing, patched some examples of using PImage, reading pixels ,serial and controlP5 together and voilà, I had the perfect little printing software for my plotter ( one can almost call it a printer now, as it doesn‘t draw vectors anyway )