The Neptune-X is a Ethernet interface card initially designed by Hirofumi Shimada, which uses popular NE2000 or its clone with its own x68k-proprietary bus to ISA bus bridge.
The
NetBSD neptune driver takes charge of the ISA bridge part of the Neptune-X. It is implemented as a more generic `bus' with its own
bus_space(9) interface, and is intended to be used with
ne(4) driver.