Bull Netstation

Introduction

The Bull Netstation was manufactured by Bull Australia beginning early 1992. I think it is OEMd from a 3Com design.

Following a global rationalisation of Groupe Bull operations, Bull Australia no longer exists.

This page gives a brief guide to setting up your main Linux system to boot Linux on the Netstation. It also includes instructions on opening the case and replacing the EPROM and making your own firmware ROM.

If you have any questions or comments, mail me.

Specification

The Netstation is powered by a 386DX-25, and has 8 30 pin SIMM sockets populated with 1Mb SIMMs. Integrated onto the motherboard are a 3Com 3C503 network card with Thinnet and Thicknet interfaces, and a ATI VGA card with 256k of video RAM. There are sockets for an additional 256k of video RAM (unfortunately they have to be SIPs, not your standard DIPs). There is no disc interface of any sort, floppy or hard.

Unfortunately it needs a keyboard plugged in to boot. Maybe someone can find the right place in the BIOS to patch to ignore the keyboard.

The serial ports are 16450 equivalent. The parallel port is only Centronics, i.e. no bi-di, EPP, EPP, etc.

Finally, it's rather unsettling to turn on a computer that doesn't have even fan whirr.

Booting

In its native form, the Netstation will attempt to boot using something called '3Com EtherStart'. I have not been able to find out anything about the protocol, and judging by the configuration screen in the BIOS I think it may assume a Netware server.

I have made a replacement firmware image that substitutes Ken Yap's most excellent Etherboot package for EtherStart. This lets the Netstation boot via the standard BOOTP protocol supported by Linux. DHCP is also supported.

If you wish to boot DOS instead of Linux, you can find instructions in the Etherboot documentation.

Setting up your main Linux system as a boot host

First you need to prepare a suitable kernel. You will need to apply a small patch to the 3C503 driver in the kernel sources. The patch is in the contrib directory in the Etherboot 4.0 distribution and can also be found here. The kernel image then needs to be tagged, or processed into the format used by Etherboot. This is done by the mknbi-linux utility included in Etherboot.

If all that sounds a bit daunting, this link will download the tagged Linux 2.0.33 kernel image I use.

Those who prefer building their own kernel may be interested in the config file I used to generate the image. You will need to specify NFS file system support, NFS for the root filesystem, and include BOOTP support. A kernel patch is available to support swapping over NFS. I have not attempted to use it.

Ken Yap's guide to setting up your server is here, and covers pretty much everything you need to know.

Some tips:

You need to find out the Ethernet address of your Bull to entry into /etc/bootptab. If you have an Etherboot ROM installed, Etherboot will report the address when it tries to boot. If you haven't yet got Etherboot installed, the Ethernet address is given on the BIOS Setup screen.
When creating the root filesystem for your Bull, don't forget /dev.
The Linux 3c503 driver will report on bootup that it is using polled mode and suggest you rejumper to use interrupts. Sadly the requisite jumpers aren't on the Bull motherboard, so you can't.
The 3c503 Etherboot driver uses the Thinnet (BNC) interface. Should you need to use the Thicknet interface, you will need to rebuild the Etherboot image after setting -DT503_AUI in the Config file and remake the ROM image. I have not tested the AUI interface - I don't have the required kit - but it should work.

Making your own ROM

The Bull has a single EPROM holding the VGA BIOS, the diagnostics, the booting software and the main BIOS. The EPROM is usually a 27C010 type, with 128k x 8bits. Some Bulls have been reported which were fitted with a different 256k x 8bit EPROM. These use exactly the same software.

The memory map of the 128k EPROM is as follows:

VGA BIOS 64k

Diagnostics 16k

Boot 8k

Main BIOS 40k

and the memory map of the 256k EPROM is:

VGA BIOS 64k

Empty 128k

Diagnostics 16k

Boot 8k

Main BIOS 40k

To generate a replacement ROM image, first make the Etherboot 3C503 image. With only 8k available, you'll need the compressed ROM image, 3c503.lzrom. Then extract the ROM components - I used split -b 8k to split the image into 8k chunks, then cat to join the split files into images for each component. I then use cat again to join the components back into a single image suitable for burning into the EPROM.

$ cat eprom-vga-bios eprom-diags 3c503.lzrom eprom-bios > bootp.dat

I recommend you use the 32bit build of Etherboot. As of Etherboot 4.0 it will generate a 8k ROM image, and you won't have to install the 16bit build tools. There is sufficient space to select the Etherboot DHCP, Message Of The Day (MOTD) and Image Menu options, but that's all. If you have a Etherboot/32 image installed courtesy of Luke McKee, those are the options in that ROM.

Matters physical

Opening it

You need a Philips screwdriver. Undo the two screws at the back and pull off the back cover. Undo the two screws holding the case towards the back and slide the case over the chassis towards the back. The two bottom supports will probably fall off at this point.

Replacing the boot EPROM

If the back of the machine is North, the EPROM located in a socket at the South-East corner of the motherboard. In this picture the business end of the screwdriver is resting on the EPROM.

The socket is rather cheap so it's best done with IC tweezers, otherwise gingerly lever it out with a screwdriver, taking care not to damage any surface mount components. Install with the notch facing the front as depicted on the silk screen, otherwise goodbye EPROM. Take care not to bend any EPROM pins. Both 128kB and 256kB EPROMs will work but it doesn't use the top address pin so 256kB EPROMs will have a blank 128kB section. See above.

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