Bill Paul has docs for this chipset, and he wrote a driver for FreeBSD.  I
ported this driver to OpenBSD without docs.  I imagine porting to NetBSD
would be a pretty simple task.

  Nathan

>  > Does NetBSD 1.5.2 support 3com 3c996-T gigabit NIC?
>  > Or is there any way to make it work?
>
> The 3c996 is based on the Broadcom BCM5700, I believe.  Until it
> is possible for a NetBSD developer to get the documentation on
> the chip from Broadcom, no driver will be possible.
>
> --
>         -- Jason R. Thorpe <thorpej@wasabisystems.com>
>