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This file is to explain the method I used to get an Explora 451 and an Explora PRO working on my network. This method should work for all thin-client machines that use TFTP to boot, but the provided downloads will only boot a PowerPC based machine. Other CPUs (MIPS, Intel, 68k, etc) will have to find kernels elsewhere (and send me a copy please.)


No - I don't want your money, or anything like that. If you have any kernels for booting other models of Explora or any other brands of thin client please email me.


Explora 700 owners can use the version of NCDware linked below.

NCDware 5.1.140 supports 16 bit colour! Download from the link below.

This site was mirrored at but seems to have gone-away now. Thanks to Jerry Wright for the service.

Juan Antonio Martinez - your email address is refusing me because "I might have ths sobig.F worm" I have not tried 5.1.140 on an Explora PRO to get 16 bit colour. I've got one dead unit here and will give it a go soon. The PRO might not support more than 8 bit colour-depth.

NCD Documentation

pexpds400.pdf Glossy on Explora 400 series.
install400-450.pdf Install document for Explora 400 series.
installFamily.pdf Install document for Explora and Explora Pro.
online51_sag.pdf NCDware System Administrator's Guide (Good Read)
ncdware50.pdf NCDware Reference Manual (Good Read)
xterminal_faq.txt Local copy

xterminal FAQ Not specific to NCD. Note the sound section
WinNT Mag story about Exploras Implies the ability to do Citrix and NT support (somehow)
Mini HOWTO for NCD Xterminals
Mini HOWTO for NCD Xterminals
NCD Techtips for NCDWare
NCD Techtips archive
NCD's FTP server Very messy unfortunately.
Xwindows on a thinstar 200
Original NCD HOWTO

Linux on Explora? Not yet... Probably never :(

Linux kernel on Explora!!! Work-In-Progress
Linux on NCD TekXPress X-terminals
Embedded linux on a PPC 403
Linux/PPC on the Explora 451


Rear Side
Bottom Side
Top Side
Booting 1
Booting 2
Power Supply Brick
Internal board

About - NCDware 5.0.129
About - NCDware 5.1.140

Hardware info

Here's some details on the guts...

Internal board

From Jimmy LE RHUN
The white connector in the middle of the board, though non-standard, is a PCI slot ! I have tested most of the pins with an ohmmeter against the AMD Ethernet chip, at least all 32 adress/data bits are there. I still miss some control signals, they may come from the PPC or the FPGA.
The two jumpers W4 and W6 near the speaker may (de)activate the rear audio output.

Now I'm not much of a component person... heres details of the internal chips.

Now - the Main Attraction...

You need the following items:

  1. NCD Xterminal.
  2. Any Unix server capable of running these services

Eeprom Config

The unit needs to know what sort of monitor you have plugged in, and what capabilities the Xserver should use. To do this, boot the Explora and press ESC at the "Searching for IP Address: DHCP" prompt. This will put you into the boot monitor - somewhat similar to Sun equipment.

The screen should look something like this:

NS0020 Video memory ................ 2 MB
NS0030 Testing DRAM memory ......... 16 MB
NS0040 Keyboard Controller ......... V1.37
NS0050 Ethernet MAC Address ........ 00:12:34:56:AB:CD
NS0070 Boot Monitor Resolution ..... 640x480   60 Hz
NS0080 Server Resolution ........... 1024x768  75 Hz

TFTP load  to abort
NS0052 100 Mbit Half Duplex
Searching for IP address: DHCP
NS0570 Connection canceled by user

Network Computing Devices EXPLORA 450 Color Boot Monitor
> []

Type ? for a list of all commands. Useful ones are pi (ping), se (setup eeprom) and rs (reset system)

Type se for Setup Eeprom

Across the top is

Help Keyboard Monitor Network Boot Done

It may help to think of this like a PC's BIOS setup. Use the arrow keys to go through all the pages making sure that all the values are reasonable.

Keyboard, Keyboard = English (US)
Monitor, Resolution = 1024x768 70 Hz This value should be based on your monitor's capabilities.
Monitor, Colour Depth = 8 or 16 bpp. NCDware 5.0.x ignores this and runs in 8 bit more. NCDware 5.1.x is required for 16 bit.
Network, Get IP Address from = Network You could use NVRAM if you don't want to run a DHCP server.
Network, DHCP IP Addressing order = 1
Boot, Boot file = Xncdxpl

DHCP server

Your Explora has no idea of what the network settings are or should be when it powers on. The user can set values in the eeprom but a DHCP server seems to be a better idea. Some of the Explora's NV ram batteries appear to be flat.

Here's my /etc/dhcp.conf file. Note - for me the DHCP and TFTP server are the same machine.

# dhcpd.conf

shared-network {
  subnet netmask {
        option domain-name "";
        option domain-name-servers;
        option netbios-name-servers;
        option subnet-mask;
        option broadcast-address;
        option routers;
        default-lease-time 81000;       # 23 hours
        max-lease-time 130000;          # one.5ish days
        allow unknown-clients;

host socks      { fixed-address;    hardware ethernet 00:50:56:40:c0:57;    }     # my workstation
host explora1   { fixed-address;    hardware ethernet 00:00:a7:04:6c:aa;    }     # explora 451
host mac        { fixed-address;    hardware ethernet 08:00:07:9c:e1:fe;    }     # junk mac for testing

You may need to use "option next-server;" to tell your clients where the tftp server will be if its a different IP to the DHCP server. TFTP is very lightweight, but some firewall distros don't offer it. You may need to look at using the NVRAM settings rather than DHCP. YMMV.

TFTP server

TFTP is Trivial File Transfer Protocol - basically a cut down FTP, without user authentication. It can be a security hole - so if your server is accessable from the net I suggest you use iptables/chains or /etc/hosts.allow and deny to control access.

Heres the line from /etc/inetd.conf that I use

#:BOOT: Tftp service is provided primarily for booting.  Most sites
# run this only on machines acting as "boot servers."
tftp  dgram  udp  wait  nobody  /usr/sbin/tcpd /usr/sbin/in.tftpd /tftpboot/ /usr/lib/X11/ncd/


This is the kernel software that the Explora gets via ethernet, then boots with that. The Explora hardware is capable of booting from a TFTP server, from local flash memory, from TCPIP, from NFS and several other boot methods.

In the NCDware archive is version 3, version 4, version 5.0.129 and 5.1.140. You only require one of the 5.x versions and can delete the other directories. I moved the complete contents of Xncd.5.0.129 to /tftpboot

You can use either 5.0.129 or 5.1.140.

Here's a listing of my /tftpboot for 5.1.140

Here's a listing of my /usr/lib/X11/ncd


Your linux/unix servers need to advertise their ability to handle logins via the XDMCP protocol. My debian box uses wdm, so to add this you need to put a line in /etc/X11/wdm/Xaccess that says:


Thats with an asterisk in the front, yes

In /etc/X11/wdm/wdm-config you need to comment out the line

  # Don't listen for XDMCP  
  # DisplayManager.requestPort:   0

Random Notes/Troubleshooting

Here's a list of random stuff:

Linux on Explora 451

Here's an email from Brad Parker
From:	Brad Parker
Subject:Re: Explora 451 project
Date:	Thu, 12 Dec 2002 15:17:40 -0500	

C Falconer wrote:
>I have obtained and distributed over 30 explora 451 units to the local
>linux users group.  Some of the members noticed your project page and
>would like to enquire as to the status of the project.

Ah. Well, the short story is it's not working.

I've done many ports of linux to various PowerPC's, including the IBM
403, but I've alway had all the documentation I've needed. In this
case the 451 has a proprietary PCI bridge inside to which the ethernet
and VGA controllers are attached.

I figured out a lot of how it works by disassembling the boot rom, but
I can't get it to work once I turn the MMU on. I'm basically stuck.

What I need is just a little help from NCD in the form of some
documentation about how the PCI brigde works. The bridge itself is
built from an FPGA, so it's custom...

I've asked NCD but never gotten a response (I've sent email to but nothing comes back).

At this point I have a kernel which will load cleanly but it can't talk
to the ethernet or vga. Not much good.

If someone can somehow convince NCD to release some docs (or code)
which talks to that PCI bridge, I'm sure I can make it run linux.
Linux has drivers for both the ethernet chip and the vga chip. I have
the memory map all figured out. The superIO chip is working (serial,
parallel, etc..).

I think there are some magic bits in the pci bridge which determine
the type of cycle it runs (i/o or memory), but which bits do what I
have no idea...

Sorry. It's a cool box. I wish it would run linux.

>My howto to get the 451 working is at 

Nice page! you'll laugh, but I've never actually run NCDWare on a 451.



Mike Pearce, Chemistry Department, University of Canterbury
Glen Cogle, Bankprint
Nick Rout, Lawyer - router
Neil "Niz" Houghton - audio
Delio - compiling kernel
Brad Parker - compiling kernel
David Caplan, aveng0 in #linux on undernet
Jerry Wright, Pacific Coast Networks
J. Seth Henry
John Gay
Alec Voropay
Fernando Reyes

Please mail corrections to C. Falconer


This file last modified Friday July 14, 2017

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