25 Years of the Model "M"
IBM's Model M keyboard is a classic.

Content by Chris McDonough (original archived HERE, last edit 2010-07-06). Modified by Major Tom.

The IBM Model M keyboard is a time traveler. You might be slightly surprised to see one on a friend's desk, as if it might foreshadow by only a few minutes the naked arrival of a Sarah Connor-hungry Arnold Schwartzenegger. Like the Terminator, the existence of a Model M today is an anachronism. In the recent past, the world used computer parts made by people in different places instead of receiving the entire trough on the slow boat from China. It still mattered more what a computer did than what it looked like. Manufacturers presumed you cared that their products last longer than a year. Trying to mend computer hardware instead of rebuying it wasn't an entirely quaint and hilarious waste of time. From such a time the Model M has traveled.

The very notion that computer hardware that began its tour of duty in the mid-1980s is still useful today seems improbable. It seems even more improbable that such surviving hardware would have moving parts. But it is, and it does. You can plug a Model M from 1987 into just about any modern computer with a PS/2 port, and it will just work. Don't worry, you'll already know how to use it; keyboards haven't changed very much since 1987. Only very recently has the availability of a PS/2 port on a computer become rare. Keyboards with USB interfaces (aka "Human Input Devices", ugh) are replacing these very quickly. But, at least for now, USB-to-PS/2 adapters are commonplace, cheap, and effective. And, as we'll see, one can even buy a Model M with a USB interface instead of a PS/2 one these days too. More on that a little later though.

The Model M keyboard is terribly fun to use, chiefly because it makes an astonishing racket while you're using it. Each keystroke of a Model M is famously loud, to the chagrin of at least two generations of spouses and coworkers. And from whence does this unholy racket emerge? Well, to begin, think about holding a slippery spring between your thumb and forefinger at a slightly oblique angle. Think about pushing those fingers together against the resistance of the spring. At some point that spring is going to buckle, and when it does, your fingers are probably going to come together rather quickly (and the spring will probably go flying across the room). Much like this, when a Model M key begins to be pressed, a little spring inside the switch assembly starts to become tensed. The spring's head is positioned at a slight angle relative to the downward force of the keypress and the angle of the spring. This angling of the spring head causes the edge of the spring during a keypress to move slightly horizontally while the spring is also being compressed downwards. As a result, about halfway through the keypress, the spring "buckles" sharply, and the side of the spring slaps against the side of the keytop barrel which surrounds it, making the famous clicking noise (the spring doesn't come flying out, because it's held firmly in place at its bottom end).

The very same thing that makes it loud is what makes it work. The angle of the spring's depression causes the bottom of the spring to push a tiny hammer down which actuates a membrane inside the keyboard chassis at the same time the spring buckles, causing a keystroke to be registered. The buckled spring holds the hammer in place, causing the controller to repeat the keystroke until the user removes force from the depressed key. When the user removes force from the key, the spring bends back into its at-rest shape. The spring provides resistance; the buckling of the spring provides tactile and auditory confirmation that the key has been pressed, as well as actuating the keypress event itself. See Ripster's informative wooden mockup for an entertaining visual demonstration of the technology, one image of which was lifted below:

Wooden buckling spring

This is known as the "buckling spring" design, and it was patented in 1978 by IBM. Most keyboards made today don't use this technology, because a) it's relatively more expensive to produce than today's generic non-mechanical rubber dome membrane keyboards and b) the buckling spring design was patented and that patent is still active today. (not true, the patent has expired).

The astonishing racket made by a Model M isn't just fun; it's also healthy. Unlike the user of most keyboards made today, a Model M user does not need to push a key all the way down in order to know that a keystroke has been registered. Instead, she can more or less let her fingers "float" on the keytops, pushing rather gently here and there. When she feels a click, she can know that a keystroke has been registered and that depressing the accompanying key any further isn't necessary. Because the user doesn't need to bottom out each keypress in order to to be sure that a keystroke was registered, less net force and motion is required during typing, reducing the potential for RSI. If you use the keyboard properly, you'll never need to press any of the keys hard enough to have one hit bottom. It's fine if you do push them hard enough to hit bottom. Mashing each key silly will still work and it's definitely fun; the mashing makes it even louder. But you needn't do it.

Another buckling spring animation

I mentioned earlier that when you plug a Model M into a new computer, you'll already know how to use it. This is because most the layout of the majority of today's PC computer keyboards was effectively based on the Model M. How do I know this? Well, just look at any old keyboard you have laying around. There are exceptions, and keyboards -- even the Model M -- have grown a couple of keys over time (a pair of "Windows" keys) but compare the layout of a 1986 Model M to just about any $7.00 yum cha keyboard of today and you will see very clearly that cheap keyboard's ancestry involves the Model M. Function keys across the top, arrow keys in an inverted T in the middle-right, a numeric keypad to the far right, Ctrl and Alt keys bracketing the space bar. That's the Model M layout. We take this layout for granted today but when the Model M was put into production, there was no similar "standard" layout. For instance, the IBM Model F was the keyboard which shipped with the original 1981 IBM PC. Take a look at the layout of a Model F sometime. Most keyboards today certainly do not copy the layout of the Model F; it has a layout dramatically different than the layout of a Model M. We just don't see any keyboards with that layout today. IBM PC clone makers were never (and still aren't) very innovative. They just did whatever IBM did. And IBM stopped bothering to make a different kind of PC keyboard layout after creating the Model M layout. The clone makers did too, 25 years ago. The Model M layout is original, in a very literal sense of that word.

Model M keyboards are ubiquitious today owing to their long production cycle and their popularity: every IBM PS/2 computer sold shipped along with one in its box. The very first Model M is rumored to have been produced in 1985, preceding the PS/2 by a couple of years. The pre-PS/2 Model Ms were sold for various industrial uses, as well as the keyboard for, in its later waning years, IBM's PC AT. Shockingly, the great majority of Model Ms produced which still exist corporeally (those which have avoided a bonfire) still function properly.

The Model M is just not built like other keyboards. It's chunky. It weighs more than two thin laptops glued together, and it's bulkier than the same pair. It's rumored that you can use one to bludgeon a man to death, then after wiping off his blood, resume working. I haven't needed to test that theory, but I can attest that the Model M can take a beating. I have a Model M keyboard built in 1987 that works well, and that looks more or less new to me (I am indeed typing on it this very screed). I have bought several Model Ms of the late 80s and early 90s vintage from EBay, each which looked like it had been stored gingerly in a wrapping of cigarette butts and Cheetos after a quick, refreshing dip in some sand. After a good cleaning, they've all looked more or less brand new and have each worked just fine.

But wait, there's more! The Model M isn't just original, loud, beefy, and durable. It's also completely fashion-deaf. In a 25 year history, it has been mass-produced in only three fabulous decorator colors: beige, industrial grey, and black. Not that it matters. Many postmodernists would think it ugly even if they could buy it in a tangerine or blueberry variant. It's OK to laugh: a Model M won't get its feelings hurt. It doesn't give a good goddamn about what you or your art major friends think of it. It has assumed a role with only two purposes: to make typing suck less, and to last forever. All other considerations are secondary. Past the first 1984 design meeting where it saw a greenlight, very little obvious consideration has been put into changing its fundamental design; certainly none due to fashion pressure.

The omission of fashion concerns over its production lifetime is one of its most important features. The Model M keyboard has simply not evolved very much. Model M keyboards have been made for more than 25 years using almost the exact same design, guts, casing and all. How do I know this, you ask? I am (shamefully) the owner of 11 Model M keyboards. Every Model M produced has a "birth certificate" on its bottom casing. It gives the day, month, and year it was produced ("making them extremely collectible," he says, by way of excuse, staring at the ground). The earliest Model M in my collection was produced in August 1986. The latest was produced in April of 1997. With a few exceptions, the mechanical parts of all of these keyboards are largely interchangeable. I can take the mechanical internals of any early-year Model M and place them in the casing of almost any later-year Model M (and vice versa) and put the casing back together; the resulting system will still work. They are the same keyboard. We're not talking about the same keyboard name or family or brand, we're talking about the same keyboard design and production for eleven years, confirmed. I can only assume that this commonality of design spans the entire 25-year lifetime. A steadfast resistance to unnecessary evolution makes them uncommonly easy to find parts for and repair.

If 25 years of staying power doesn't impress you, this should: its story hasn't ended. New model Ms are still being produced today in Lexington, Kentucky, United States by a company named Unicomp. I don't mean that Unicomp just bought the Model M copyrights (which they did) and rights to use the buckling spring design (which they did) and began innovating with new designs only marginally related to the older Model M (which they did not), attempting only to capitalize on brand recognition (of which there is little, I fear). I mean that they bought the factory, tool and die. Unicomp's website won't win any prizes, but they crank the same exact keyboards out that were being cranked out in 1986 today with two minor exceptions: you can now buy a keyboard with Windows keys and you can buy a Model M with a native USB interface. These aren't "copies" of a Model M; these are Model Ms. Even the addition of Windows keys or the new interface doesn't mean very much: the Unicomp spring assemblies still fit in the a Model M case from 1986, and vice versa. You can even buy parts from Unicomp to fix your 1985 Model M. Unicomp's new keyboards aren't the cheapest: they start at $69 for a basic bucking spring model. But, then again, if you enjoy using a keyboard, and it will last you for 25 years, almost any price is a huge bargain as far as I can tell. Would it really matter if you paid even $250 for it, given a presumption of that time scale?

Computers and other consumer electronics are one of today's ultimate disposable, temporary goods, second only in their impermanence to software. Fifteen years ago, I found it hard to buy the same computer cases from month to month while building PCs. I can only imagine what trying to do that is like today. But if you think about it, a keyboard that has a twenty-five year lifecycle is as obvious as the sun. Until we get ubiquitous voice recognition, we're all going to need some form of easy input to a computer: a keyboard is about as good as it gets as an input device for now. Why shouldn't a keyboard have a lifetime longer than a dog's? Certainly, you only need as many keyboards as you have computers (except when you need 11 of them... ahem) and the Latin alphabet certainly isn't going to change during its lifetime.

In summary, I ask you, good sir: what useful piece of computer hardware could you buy off the shelf in both 1985 and today? I thought so. Here's to the Model M after 25 years.

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