I've ported to NEC EWS4800/350 and EWS4800/360ADII.

source(patch) and snapshot are
ftp://ftp.netbsd.org/pub/NetBSD/misc/uch/ews4800mips*

[350 install]
 350 don't support IBM-PC type floppy. You need EWS-UX to prepare
boot floppies.
# ifformat /dev/rif/f0h
# dd if=boot1.fs of=/dev/rif/f0h bs=8k
# dd if=boot2.fs of=/dev/rif/f0h bs=8k
 Or write floppy image to hard disk, and then boot from disk.
# dd if=boot2.fs of=boot2.fs.noheader bs=8k skip=1
# cat boot1.fs boot2.fs.noheader >boot.fs
# dd if=/work/boot.fs of=/dev/rsd0d bs=8k

 IPL tips.
 Power on holding ESC key.
 BO command selects boot device.
 Floppy boot. -> 0
 Disk boot    -> 2
 boot form Disk 1 -> 2 1

[360 install]
 360 supports IBM-PC type floppy. but IPL option is required.
 boot from IBM-PC format floppy -> 0 -M 1
 Disk boot -> 2
 boot from Disk1 -> 2 -I 1

[NFS boot]
 You need to compile bootloader embeded kernel.

cd sys/arch/ews4800mips/stand/common;nbmake-ews4800mips
cd sys/arch/ews4800mips/stand/boot
INCLUDE_KERNEL=../../compile/GENERIC nbmake-ews4800mips

 * EWS IPL try to load fixed name "boot".  "filename" option is ignored.

[350 dmesg]
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

FB enabled.
NetBSD 2.0F (GENERIC) #10: Sun Jun 27 02:26:35 JST 2004
	uch@alexandrite:/work/cvsrep/src/sys/arch/ews4800mips/compile/GENERIC
NEC EWS4800/350 (TR2) 50MHz
total memory = 49152 KB
avail memory = 45696 KB
mainbus0 (root)
cpu0 at mainbus0: MIPS R4000 CPU (0x422) Rev. 2.2 with MIPS R4010 FPC Rev. 0.0
cpu0: 8KB/16B direct-mapped L1 Instruction cache, 48 TLB entries
cpu0: 8KB/16B direct-mapped write-back L1 Data cache
cpu0: 1024KB/64B direct-mapped write-back L2 Unified cache
sbd0 at mainbus0
osiop0 at sbd0 at 0x1b050000 irq 5 : NCR53C710 rev 2, 25MHz, SCSI ID 7
scsibus0 at osiop0: 8 targets, 8 luns per target
iee0 at sbd0 at 0x1b060000 irq 6 : Intel 82596CA address 00:00:4c:11:ac:4c
iee0: reseting chip... done.
kbms0 at sbd0 at 0x1b010000 irq 0
wskbd0 at kbms0: console keyboard
wsmouse0 at kbms0 mux 0
zsc0 at sbd0 at 0x1b011000 irq 2
zstty0 at zsc0 channel 0
zstty1 at zsc0 channel 1
fb0 at sbd0 at 0xf0000000, 0xf5f00000
wsdisplay0 at fb0 kbdmux 1: console (std, vt100 emulation), using wskbd0
wsmux1: connecting to wsdisplay0
scsibus0: waiting 2 seconds for devices to settle...
sd0 at scsibus0 target 0 lun 0: <FUJITSU, MAJ3091MC, 0114> disk fixed
sd0: 8714 MB, 13262 cyl, 3 head, 448 sec, 512 bytes/sect x 17847486 sectors
sd0: sync (160.00ns offset 8), 8-bit (6.250MB/s) transfers
sd1 at scsibus0 target 1 lun 0: <FUJITSU, MAJ3091MC, 0114> disk fixed
sd1: 8714 MB, 13262 cyl, 3 head, 448 sec, 512 bytes/sect x 17847486 sectors
sd1: sync (160.00ns offset 8), 8-bit (6.250MB/s) transfers
root on iee0
mountroot: trying nfs...
nfs_boot: trying DHCP/BOOTP
iee0: reseting chip... done.
iee0: reseting chip... done.
iee0: iee_watchdog: setup timeout 1
iee0: reseting chip... done.
nfs_boot: DHCP next-server: 192.168.33.2
nfs_boot: my_name=erlik
nfs_boot: my_domain=s.vnop.net
nfs_boot: my_addr=192.168.33.24
nfs_boot: my_mask=255.255.255.0
nfs_boot: gateway=192.168.33.1
iee0: reseting chip... done.
iee0: iee_watchdog: setup timeout 2
iee0: reseting chip... done.
root on 192.168.33.2:/work/ews4800mips/nfsroot
root time: 0x40ddb681
rtc=0x40ddb67f base=0x40ddb681
WARNING: preposterous clock chip time
2004/6/26/17/46/41(6) rtc_offset 0
 -- CHECK AND RESET THE DATE!
root file system type: nfs
init: copying out path `/sbin/init' 11
nfs_send: proc botch: rep 0x0 arg 0x0 curproc 0x80408330


[360 dmesg]
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

FB enabled.
NetBSD 2.0F (GENERIC) #11: Sun Jun 27 02:58:46 JST 2004
	uch@alexandrite:/work/cvsrep/src/sys/arch/ews4800mips/compile/GENERIC
NEC EWS4800/360ADII (TR2A) 200MHz
total memory = 192 MB
avail memory = 184 MB
mainbus0 (root)
cpu0 at mainbus0: MIPS R4400 CPU (0x460) Rev. 6.0 with MIPS R4010 FPC Rev. 0.0
cpu0: 16KB/32B direct-mapped L1 Instruction cache, 48 TLB entries
cpu0: 16KB/16B direct-mapped write-back L1 Data cache
cpu0: 1024KB/128B direct-mapped write-back L2 Unified cache
sbd0 at mainbus0
osiop0 at sbd0 at 0x1e500000 irq 6 : NCR53C710 rev 2, 25MHz, SCSI ID 7
scsibus0 at osiop0: 8 targets, 8 luns per target
osiop1 at sbd0 at 0x1e510000 irq 10 : NCR53C710 rev 2, 25MHz, SCSI ID 7
scsibus1 at osiop1: 8 targets, 8 luns per target
le0 at sbd0 at 0x1e400000 irq 0 mem 0xa07c2000: address 00:00:4c:b1:45:a9
le0: 8 receive buffers, 2 transmit buffers
kbms0 at sbd0 at 0x1e480000 irq 9
wskbd0 at kbms0: console keyboard
wsmouse0 at kbms0 mux 0
zsc0 at sbd0 at 0x1e440000 irq 4
zstty0 at zsc0 channel 0
zstty1 at zsc0 channel 1
fb0 at sbd0 at 0xf0000000, 0xf5f00000
wsdisplay0 at fb0 kbdmux 1: console (std, vt100 emulation), using wskbd0
wsmux1: connecting to wsdisplay0
scsibus0: waiting 2 seconds for devices to settle...
scsibus1: waiting 2 seconds for devices to settle...
sd0 at scsibus0 target 0 lun 0: <FUJITSU, MAJ3091MC, 0114> disk fixed
sd0: 8714 MB, 13262 cyl, 3 head, 448 sec, 512 bytes/sect x 17847486 sectors
sd0: sync (160.00ns offset 8), 8-bit (6.250MB/s) transfers
sd1 at scsibus0 target 1 lun 0: <FUJITSU, MAJ3182MC, 0114> disk fixed
sd1: 17429 MB, 14809 cyl, 5 head, 482 sec, 512 bytes/sect x 35694904 sectors
sd1: sync (160.00ns offset 8), 8-bit (6.250MB/s) transfers
root on sd0k dumps on sd0b
mountroot: trying nfs...
mountroot: trying lfs...
mountroot: trying ffs...
root file system type: ffs
init: copying out path `/sbin/init' 11