I haven’t played much with the ActionPrinter 2000 dot-matrix printer since last year. I had gotten MESS to emulate the printer’s firmware and used that to simulate the system’s printer using MESS, but the whole procedure was still kind of complicated, requiring exporting a bunch of logging information to a text file and using a script to convert that to a picture.

I finally got over my laziness and implemented an output device to simulate the paper being printed out directly in MESS.

The paper emulation is actually pretty simple and dumb. A big bitmap is populated with the dots from the printer when the printhead fires. The lines in the bitmap form a circular buffer, and when paper is “pulled” from the printer, it just updates an index that points to some line in the buffer and clears the next line. MESS already had support for scrolling bitmap that by using the copyscrollbitmap() function.

This only covers continuous paper though… What I really want is to implement a paper_t class (subclassing device_t), which can have proper paper dimensions (A4, letter, etc…) and interacts with the paper-end sensor. That way, I hope to be able to output PNGs and PDFs directly from MESS.

The problem is that I haven’t had access to the real printer for an year and a half, and I don’t remember how the sensors and the paper interact =/. I’m trying to get my hands on a similar printer to continue working on this. Hopefully, it won’t take another year before I figure this out…