I am new to NetBSD and have successfully installed NetBSD 1.2 on my sparc 2.

congrats!
   
   Then I have set boot-file to netbsd and boot-device to /sbus/esp/sd@3,0 (because I want
   to boot from unit 0, which is remapped to 3). When booting with these settings, it
   seems that the bootblock is loaded but it cannot proceed and stops with the prompt
   boot:

   Please help me how I can use my old SunOS 4.1.3_U1 on disk with id 3 and boot
   NetBSD form the disk with id 0.

i think you want to set the boot-device to /sbus/esp/sd@0,0 -- that
"boot:" prompt is from the sunos bootblocks, and it is what would
happen if there was no file called "netbsd" in the root filesystem.


note:  `disk0' is probably an alias for /sbus/esp/sd@0,0.  my boot
disk is on SCSI id2, and i use `disk2'.


hope this helps,


.mrg.