[tulip] No Link Beat on Cable Modem

[David]

I have an SMC 8432 (Tulip 21041-based) ethernet card and cable modem
from AT&T of Colorado.  In Win95, they set a special option on the
driver to tell it to not look for a link beat, since the cable modem box
(RCA model DCM205) does not generate a link beat.  When I boot Linux
with the tulip driver, I get this:

kernel: eth0: No 21041 10baseT link beat, Media switched to 10base2.
kernel: eth0: No 21041 10baseT link beat, Media switched to 10base2.

When I try to force it to 10baseT (modprobe tulip options=12 debug=6),
this is 
what I get:

tulip.c:v0.92t 1/15/2001  Written by Donald Becker <becker@scyld.com>
  http://www.scyld.com/network/tulip.html
eth0: Digital DC21041 Tulip rev 33 at 0xd0015000, 00:E0:29:61:67:16, IRQ
9.
eth0: Transceiver selection forced to 10baseT(forced).
eth0: 21041 Media table, default media 0800 (Autosense).
eth0:  21041 media #0, 10baseT.
eth0:  21041 media #4, 10baseT-FDX.
eth0: tulip_open() irq 9.
eth0: 21041 using media 10baseT, CSR12 is 00c4.
eth0: Done tulip_open(), CSR0 ffe08000, CSR5 fc120000 CSR6 fffe2002.
eth0: interrupt  csr5=0xfc670004 new csr5=0xfc660000.
eth0: exiting interrupt, csr5=0xfc660000.
eth0: interrupt  csr5=0xfc670004 new csr5=0xfc660000.
eth0: exiting interrupt, csr5=0xfc660000.
eth0: interrupt  csr5=0xfc670004 new csr5=0xfc660000.
eth0: exiting interrupt, csr5=0xfc660000.
eth0: interrupt  csr5=0xfc670004 new csr5=0xfc660000.
eth0: exiting interrupt, csr5=0xfc660000.
eth0: interrupt  csr5=0xfc670004 new csr5=0xfc660000.
eth0: exiting interrupt, csr5=0xfc660000.
eth0: Media selection tick, 10baseT(forced), status fc660000 mode
fffe2002 SIA 000020c6 ffffef01 ffffffff ffff0008.
eth0: 21041 media tick  CSR12 000020c6.
eth0: Media selection tick, 10baseT(forced), status fc660000 mode
fffe2002 SIA 000020c6 ffffef01 ffffffff ffff0008.

I can't ping anything, even the router.  When I rrmod the tulip driver,
insmod my ancient but trusty NE2000 clone, and plug the ethernet cable
there, everything works, so it's not my Linux setup.  I'm using kernel
2.2.18
on a Slackware 7.1 distribution, although I had the same problem with
a Red Hat 6.2 distribution.

I'd appreciate any help anyone can give me.

-Dave