IBM PS/2 L40 SX (8543)

[ L40 SX ]

This portable computer served me well since 1996. I bought it second-hand and only got a photocopy of the Quick Reference guide, so I decided to run the copy through a scanner and save the text and the illustrations to PDF format.

It is proofread a couple of times and should be an exact reproduction of the original document, but you use the information at your own risk.

Quick Reference (960KB, 120 pages)

Hints and Tips (44KB, 4 pages)

Battery Life Guide (44KB, 4 pages)

Print setup for these 3 documents: Page width = 130mm, page height = 200mm. (About 5 in. and 8 in.). Try printing 2 pages per A4 or Letter sheet in Landscape, and select "Fit to Page".

Service Manual (147KB). The L40 SX specific information, taken from the "Portable Computer Information document vol. 1" at IBM.


The rechargeable battery pack is an expensive part. It holds a total of 18 nickel-cadmium cells (2x9) that will need replacing if you buy a +10 year old computer. I have substituted the special-size cells with cheaper standard AA-size cells. It gives 45-60 minutes of portable operation, depending of the quality of the cells - not enough for serious portable use, but fine if you only want to keep the computer in a working state for fun.

NiMh batteries has a slightly different voltage than NiCad, and the L40SX computer will sound the first alert with about 15 minutes left, when using a battery pack in mint condition.

A new NiMh battery pack using cheap standard cells will last a couple of years when the computer is used on a regular basis.

The nominal output from the AC adapter is 14,3 - 15.8 V DC, so you can make your own power supply or a car battery adapter at a low cost.

It will work with a standard 80387 co-processor from an old 386 motherboard if you find one, but the RAM is special.

Windows 3.1 knows the hardware and will modify the config.sys and system.ini files during installation as described in the Hint and Tips document. Running Windows 3.1 in "standard mode" with 2MB RAM is very slow, but old DOS software like WordPerfect 5.1, AutoCad 10 (needs co-processor), Norton Commander 4, FastLynx, Paradox 4.5 and lots of old games runs fine.

More downloads

IBM has discontinued service for this portable computer a long time ago, and has no driver downloads, spare parts sale or service manuals on their websites.

Download rfl40103.exe (500KB) to make the Reference Diskette or download (500KB) and unzip, if your network or browser setup prevents you from downloading executable files.

The executable works in DOS, OS/2 and 32-bit Microsoft Windows, creating a bootable 1.44 floppy diskette for configuration and test of the L40SX computer. Download the Quick Reference PDF and follow the instructions for use of the Reference Diskette starting on page 43.

IBM also distributed a presentation of the L40 SX computer. It will fit on a 1.44 floppy or can be run from a command line in DOS, OS/2 and Windows (also Windows XP). Download (900KB) - unzip, run laptop.exe and enjoy the VGA graphics made by The SoftAd Group in 1991.


The harddrive in my L40SX had difficulty spinning up for some years until it stuck. A service life of 20 years is probably more than any modern PC can manage.

My L40SX was disposed as toxic waste 2014-04-10. Its software was already backed up and transferred to a virtual machine.

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