To talk to the Laserjet, I decided on using the Centronics parallel port. I could have used the serial port too, but I remembered the parallel port protocol was easy to implement, and the Centronics-port was said to have a +5V from the printer available. That would help me a lot because I wouldn’t have to find an external supply of power for the microcontroller. For the microcontroller itself, I decided on my good old pal the ATTiny2313. I could have used an other avr, but I’ve got dozens of this type laying around and they’re cheap enough, so I decided on this one.
Standalone printer hack