As Gordon W. Ross <gwr@mc.com> (and probably others) said, one of 
my problems was tftpd seems to run in chroot mode in this Ultrix box 
(BTW, the -r is to indicate the path of the tftp'able directory).  So, I 
copied netboot to [.../tftpboot, remade my links and advanced one more 
step to get this working.  So, now we are in the following step:

>b le() -s
Boot: le(0,0,0) -s
Using IP Address 128.227.42.13 = 80E32A0D
Booting from tftp server at 128.227.42.155 = 80E32A9B
Downloading 13312 bytes from tftp server

>> NetBSD netboot [$Revision: 1.2 $]
Requesting Internet address for 8:0:20:0:1D:35
/

Why would it want to request an internet address *again* (8:0:20:0:1D:35 
is the ethernet address of the machine BTW)?  Hmmmm...

-- 

 ===========================+=============================================
| Mauricio Tavares          | "We will attack...                          |
| raub@kushana.aero.ufl.edu |  ...under the cover of daylight!" Rimmer    |
 ===========================+=============================================