i82586-based controller, similarily to e.g. ai(4), el(4) or ix(4).
The driver was modelled after the ai(4) driver.
Due to lack of better documentation, Linux 3c523 driver was used
to find out 3c523-specific quirks. Of course, the necessary work was greatly
reduced by our decend generic ic/i82586 code :)
Finally, NetBSD supports an ethernet card on IBM PS/2!
