Care and feeding of the IBM Model M keyboard

Restore a Model M to good-as-new condition! Contents:

About the 1391406 / 1391401

Ah, the mighty IBM Model M—the best keyboard ever manufactured. The Model M was originally bundled with 8086 and 80286 IBM PS/2 computers dating from around 1986. The design has not been improved on since. Fortunately the Model M is so durable and well-made that a vintage 80's keyboard will likely still be usable today (note: written in 2004), after a decade and a half and of use and abuse.

The M's key feature is it's wonderful clicky feel. Tap a Model M key and it lets out two clicks, as the key is depressed and then released, click-CLACK! The Model M gives a wonderful tactile feel of connection with the keyboard—as you depress a key, the weight required to generate a character is just right. Why would anyone be a keyboard evangelist? Use a Model M and all will become clear!

I've always said you should spend the most money you can afford on the parts of your computer that you come into contact with. This means getting the best keyboard, mouse, and monitor you can afford. Sure, you can buy cheapo equipment, but it won't last very long and you won't get the best use out of your machine—buy a Model M now, and you'll still be using it when every other part of your computer has worn out or been replaced by upgrades.

The Model M weighs in around 2.25 kg / 5 lb depending on the exact model, and absolutely will not move around on your desk while typing. Usefully, it's the only keyboard you could use to beat someone to death if you're ever caught in a tight spot with only computer peripherals to defend yourself. Compare with the flexible, squishy, rubbishy "multimedia" keyboard you can buy at any old computer store. No "Windows" keys here, no "sleep" key waiting to be pressed accidentally, a proper full-size space bar, and long backspace key. Yes! The Model M is a colossus among keyboard-kind.

Possibly, the only cooler keyboard is the original IBM PC-AT 84-key board. This is a real monster, being even heavier (~2.8 kg) and more clicky than the Model M. These things are ancient as Moses, dating from around 1984. Yeah, I want one, even if it requires a PC-AT to actually work. The PC-AT works fine with a PS/2 compatible using an AT-PS/2 converter (my thanks to Damian Walker for this correction).

Buying an M

Note: mid-2000s prices are wildly out of date and included for your amusement, gentle reader. UK-layout Model M boards pop up regularly on eBay.co.uk, at the time this page was written in 2004 these sold for around £20 each (really). Prices for vintage models at the time of writing (last checked 2022) are around £110-150 depending on condition. You may find USA-layout models more cheaply, but international shipping can be a problem (2.25 kg of plastic and metal, remember). In the 2000s there were a few other places selling them—including The Keyboard Company for £29, clickykeyboards.com had mainly USA-layout models around $40-50, and pckeyboard.com had the modern Unicomp remake of the Model M with the same keyboard feel for $49 for a USA one, $79 for a board with UK layout.

Buying a Model M in 2023

Please be aware that in 2023, original / vintage IBM and Lexmark manufactured Model M keyboards are collectors' models. Still recommended reading if shopping for a vintage M is the Model M buyer's guide at clickeykeyboards.com (Wayback Machine link).

As of late 2020, Unicomp have made significant changes to refresh their tooling, design, and update the USB controller in their reproduction Model M keyboards. The result is the 'New Model M' keyboard priced at $104. If you are shopping for a Model M for typing on rather than as a collector, this should absolutely be the first thing to you look at. My thanks to Eric S. Raymond for alerting me to this.

Distinguishing features

Mine is a type 1391406 Model M manufactured in the UK in 1989. This is the UK variant of the "International" keyboard layout—the international Model M has an L-shaped enter key with an extra key nestling in it's crook, so it's 102 keys total.

My M is an old-school board made in Scotland by IBM United Kingdom, there are later model 1391406 keyboards made by Lexmark which have a blue IBM logo and fixed keyboard lead, these were made from 1993 onwards. They are not as nicely made as the IBM-manufactured ones. I understand 1391406s are comparatively rare in the USA, where you are more likely to see the good ol' models 1391401 or 42H1292. Consider yourself elite if you can find an M with the 12' keyboard cord.
UK 102-key layout: large enter key, £ shares a key with 3, ' shares with @, and ~ with # (links to a larger version).

"Birth certificate"—Model M type 1391406, made in Scotland in 1989 and still going strong. Rear view. The grille is vestigal, and on a Model M variant shipping with IBM's RS/6000 workstation housed a speaker (thanks to Eric S. Raymond for confirming this after many years of uncertainty) (links to a larger version).
Removable PS/2 keyboard cord for ninja mobile Model M swapping. Battle damage. What happened? Someone dropped it, or maybe a stressed office worker finally had enough and went on the rampage with their trusty keyboard...

Disassembly and cleaning

Taking apart and cleaning a Model M is relatively easy, I advise setting aside about an hour to do the actual disassembly and cleaning the parts, as well as time for the parts to dry. You only need one proper tool, a 5.5mm (7/32") nut driver like this one. After being told by the chap in my local hardware shop that, "I've never seen a 5.5 mil one, I don't think they exist!", I just bought one online from axminster.co.uk. You need a thin-walled nut driver because three of the nuts that hold the two halves of the Model M together are deeply recessed, a normal socket is way too big. I suggest taking the M apart before removing the keycaps.

Other stuff handy to have:
Anyway, undo the four nuts and put them in a safe place. Lift off the top half of the keyboard's shell and undo the nut that fixes the metal plate holding the keys to the lower half of the keyboard shell. Your M has has likely accumulated a variety of hair, crumbs, dust and other grim stuff over it's life, so laying down newspaper before taking it all apart is a good idea. I can't resist showing you a few "before" pictures of the gribbliness I was dealing with:
Pictures link to zoomed-in versions (large!).
Model M keycaps come in two parts, so just pop off the top halves of the keys with your fingers—you shouldn't need to use a knife to pry them off. This exposes the smaller keys you can see in the pictures above and to the right. I suggest leaving these on and cleaning around them, best to minimise the exposure of the bucking-spring innards to dirt.

Take care removing the larger keys (shift, space bar etc.) as they don't have the same small inner keys. Some other guides to Model M cleaning recommend leaving the Caps Lock key in place as it's apparently easy to break while removing. I popped the Caps Lock off with my fingers without breaking it, so…
Picture links to a larger version.
Picture links to a larger version.
Now you have your parts. I put the keycaps in to soak in hot, soapy water in the sink while I dealt with the M's main board. First give it the once-over with air duster, then wipe with a soft, damp cloth to remove the worst of the dirt. I used dampened cotton buds to clean in between the keys, then went at the really stubborn dirt with a cotton bud and a little isopropyl alcohol.

Meanwhile, back to the keys. My keys had some horrible ingrained grime, so I had to scrub each one individually to get it all off. It took forever, but those keys practically shone afterward. When you've done this, scrub the two halves of the shell of the keyboard in hot, soapy water. Be careful with the label on the back of the M—this is it's "birth certificate" and something buyers should look for if you ever want to sell your board. If you are really worried, get a bit of plastic and duct tape it over the label to keep it dry.

Leave your keys and halves of the shell to dry on newspaper (finally, I find a use for the Grauniad travel section), and do something useful with the time. Maybe start that Web page about your keyboard?

Reassemble in reverse order.
All clean! (Links to a larger version.)
By now you have a nice, clean Model M restored to pristine condition—stop a minute to admire your handywork. :) Sadly I wasn't able to get all of the dirt out from around the edges of the IBM logo, and it doesn't seem to be removeable. Any suggestions? With occasional cleaning, and barring lump-hammer attack, a Model M will last decades. in fact the only addition I see being useful in years to come is a dongle to convert a Model M to USB, for when all motherboards have gone 'legacy free' (feh). I'm sure you've been waiting for this bit, so onwards to the cheesecake photos of the clean M:
These pictures link to larger versions

Links to more Model M pages

The Compleat Classic Keyboard Technical information and troubleshooting guide from Eric S. Raymond
clickeykeyboards.com New and used Model M buyer's guide, some nice general info. (Wayback Machine link)
pckeyboard.com
 New keyboards made to a similar specification and same keyboard feel as the Model M.
modelm.org Some wonderful stuff about Model M modification (Wayback Machine link).
PS/2 Keyboard A wealth of information about the Model M (Wayback Machine link).
Converting an M to Dvorak layout The Model M is curved, but that's achieved by the metal plate the keys sit on being curved. The keycaps themselves are all the same and can be swapped about at will.
Dan's Data Model M review
Dan's Data Model M review II An updated review, covers several Model M variants.
Model M USB upgrade Solder on a PS/2 to USB adaptor at the keyboard end, and you have Ico Doornekamp's 'almost native' USB Model M (Wayback Machine link). Note: do not do this to a vintage Model M today, instead buy a 'New Model M' from Unicomp.
Model H: IBM USB keyboard conversion John Hawthorn's open source replacement for the Model M controller board that adds native USB capabilities. The wonders of modern PCB prototyping.
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