For a Linux 1.2.13 kernel, the following instructions explain how to get the card activated. To use the driver, you need to uncomment a line in the script that is used when you do a "make config" to reconfigure the kernel. The line is located in the file "/usr/src/linux/arch/i386/config.in" and the line you want to edit reads:
# bool 'DEC 21040 PCI support' CONFIG_DEC_ELCP nRemove the '#' character at the start of the line, then return to /usr/src/linux and run "make config". Make sure you ask for PCI support and for PCI LAN cards.
On some distributions, the driver, which should be in usr/src/linux/drivers/net/tulip.c may not be in that location when the system is installed. If not, it'll be necessary to unpack the kernel sources package onto your disk. In the kernel sources area, you'll find the same directory structure, and will find the tulip.c file there. Simply copy it to the location I mentioned above, then do the kernel build.
Performance seems quite good on this adapter, living up to expectations of a PCI based solution. The card has 10BaseT and 10Base2 interfaces. Depending on the version of the tulip driver you have, you may need to patch the driver to make the 10Base2 interface function. Read the Linux and the DEC "Tulip" Chip page for more information on how to do this, and for any new developments on this driver.