ELKS Linux with the Commodore C286-LT Laptop

This document is a side effect of two other projects I worked out. First the Linux-Ecology-HOWTO: "The Ecology-HOWTO discusses ways Linux computers can be used as a mean to protect our environment, by using its features to save power or paper. Since it does not require big hardware, Linux may be used with old computers to make their life cycle longer. Games may be used in environmental education and software is available to simulate ecological processes." And second the Linux Mobile Guide - Installing, Maintaining and Tuning of Linux on Mobile Computers.

If you search a Linux port for 286 CPU look at ELKS . If you like, you may also use Minix one of the predecessors of Linux. Minix supports 8088 to 286 (and better) CPUs with as little as 640K memory.

Installation of ELKS

Installation of ELKS on the Commodore C286-LT was pretty straightforward. I took the binary ZIP image of ELKS 0.0.77 . Unpacked the file and used rawrite2 to build the boot and root floppy. Put the boot floppy into the drive. Started the laptop. Changed to root floppy. Logged in as root without a password. Did ls /bin and found vi. Started to edit c286lte.html, which is this file actually.

Recently I changed to 0.0.79 and put ELKS on the hard disk. It works fine. I still boot from a floppy, but I will try to get around this, too.

When I have some more time I will describe the installation in more detail. Just some caveats:

• Read the ELKS FAQ first.
• Use fdisk /dev/bda (not /dev/hda) to make the partitions on the hard disk.
• Use MAKEDEV to build the device files. You may copy the other files from the image to the hard disk. Don't forget to sync after all files are copied.
• To boot from the hard disk you can't use the provided images. Build a new kernel as described in the ELKS FAQ.

Hardware

BIOS

Rev 1.3 390854-01 (PHOENIX 80286 ROM BIOS PLUS VERSION 3.10.00 - 11, partly from Award and Cirrus). You get the BIOS setup by pressing <CTL><ALT><ESC>

RAM

The BIOS reports: 640K Base Memory, 00384k Extended

Hard Disk

2.5" 20MB Conner CP-2024 (653 or maybe 635 cylinders , I got different information, precomp: none, 2 heads, 32 sectors, automatic parking, maybe the only hard disk with 8-Bit XT-Bus interface,
BIOS parameters for the hard disk are: number 2, cyl 615, heads 4, sect 17, pre 300 lz 615

Hardware Maintenance

Opening the Case

• turn the backside up
• remove three screws near the front side
• turn the case back
• remove the keyboard (don't forget to lift the two cable lockers first, if you want to remove it completely)

RAM

• You may insert two 2MB RAM modules easily (the machine comes with 1MB).

Removing the Hard Disk

• remove three screws of the aluminium shield which covers the hard disk at the left side
• turn the machine to the backside again and remove the four (covered) screws, which hold the hard disk
• turn the machine back
• lift the aluminium cover at the left side and pull it to the left
• remove the cable (don't forget to lift the two cable lockers first)
• remove the hard disk

BIOS and Battery

• The BIOS battery is easily accessible from under a cover at the back of the computer. You have to remove the main battery first.
• Didn't look for BIOS and the memory, because they seem more hidden. If you like to give it a try additionally remove three screws under the main battery first.

Power Supply

The label on the power supply looks like this:

input 100-240V~50/60 Hz 1.0A
output 16V --- 1.5A
fuse T3.15A

From Andreas Beutling I have got this report in German. All errors from the translation to English are by me. Here is his report in German and some additions about updating the RAM.

"... this notebook is still complete and working fully. It has been slightly improved with a 500MB harddisk and a second serial port (selfmade) in the modem slot. Also the original power supply is available. For the almost equally equipped C386LT an original service manual is available.

About the power supply: This device is not a common power supply, it is a combined charge and power supply with an integrated, intelligent charge chipset. The notebook itself has nothing to do with charging the battery, this is done completely by the power supply. A long time ago I have dismanteled it completely, because I have supposed something broken. I could detect the following features: The battery will be only charged, if the notebook is powered off. During the charge time the charge LED at the power supply is on, after that is goes off. The charge LED at the notebook is always on, when the power supply is connected und supplies voltage - no matter whether charging or normal operation. The charge operation follows different steps. First the battery is charged with a very low currency (app. 30 mA), exactly for five minutes. Only than the real charging starts, with app. 250 mA. Every twenty seconds the chipset loads additional 250 mA, until after some minutes the maximum of 2,5 A is reached. With this currency the battery is charged until "battery full" is detected, the end of charging is probably detected via Delta-U.

The label on the box of the power supply is more or less covering the actual numbers, because they don't fit. The power supply can be easily replaced by a simple panel, which can supply the notebook (therefore 12V at > 500 mA is enough) and than delivers a limited currency (app. 15 V) for charging, but a charge currency control and finish panel would be better.

My machine take app. 500 mA, and therefore runs with one battery load almost four hours. But this time I have only reached after changing the original hard disk with a modern and less power taking 500 MB hard disk.

Mini-DIN-Plug for the C286LT/386LT (Power Supply)

View to the slots in the plug of the machine, or to the soldering site of the plug, marked (notch) at the bottom:

 8  7  6
 
5   4   3
 
 2     1

Table of connectors:

1, 2   ground (GND)
3      contact of the main switch to ground (normal=off open), will be
       looked up by the power supply
4, 7   work currency normal usage (12-16 V, 1,5 A)
5, 8   charge currency battery (up to 18 V, 2,5 A)
6      ground, comes from the power supply into the logic of the notebook

Please note with selfmade in-built power panels, that the connector 5/8 isn't connected directly at battery-plus, there is a diode type ERD64M-004 in between. Also you should know, that the connector 4/7 is always connected with the battery currency, but reduced by an additional diode of the same type. This connector is connected from the main switch into the machine.

Maintenance

C64 & More offers replacement backlight bulbs, power supplies, manuals etc.

Minix

I have tried to install Minix v2.0.3 but with no success yet.

FreeDOS

Just for fun I have also installed FreeDOS. It worked out of the box.

ToDo

I will follow the ELKS project. Maybe I will give Minix another try, too.

Resources

• The COMMODORE Place - C286-LT
• The COMMODORE Place - C386SX-LT
• Unix Laptop Survey (Commodore)
• TuxMobil - hardware section
• Linux Mobile Guide - Installing, Maintaining and Tuning of Linux on Mobile Computers

Credits

Thanks to

• Verena Lorenz-Meyer for providing the laptop.
• The members of the ELKS Linux project.
• The members of the <linux-laptop_at_vger.rutgers.edu> mailing list.
• Gaute Hvoslef Kvalnes <386_at_altavista.net>
• Falk Nagel <falk.nagel_at_tu-clausthal.de>
• Harry Kalogirou <harkal_at_rainbow.cs.unipi.gr>
• Andreas Beutling