RedNova & -D-
the 712c required something "special" that the amiga drivers didn't support.
The 712c is a Windows Host based printer (PPA I think they are called). They don't use PCL or Postscript per se. I had a 722c once which is similar and got it working using pnm2ppa which uses Ghostscript, but I did it over a network from the Amiga through a Windows host. Not sure if pnm2ppa is available with the Amiga Ghostscript package.