<p>I picked up my HP 4480s for 5 USD each – but, more importantly, HP appears to be using the same print engine between several models – I have found between 3 HP models of different vintages (+/- 3 years) the same sheet metal, drive, and scanner components, and much of the same wiring.</p>
<p>The printhead carriers and on-board logic seem to be designed by the same group for all of my sample HP inkjets, so I think it would be safe to say that if we can figure out one, the rest should be minor variations on that theme.</p>
<p>I’ll break out my oscilloscope over the weekend to verify that the logic pulses are within 3.3v or 5v signalling parameters, then hook up an FTDI as a poor-man’s logic probe to see if I can get traces on all the logic pins for the HP Demo Page.</p>
<p>Wish me luck.</p>