My keyboard has over a hundred keys on it. But there's one labelled NumLock. Pressing it turns the numeric keypad into a duplicate of the dedicated arrow keys just left of it. This doesn't seem useful to me...

Does anybody know how this strange state of affires came about? Was there a time in history when NumLock actually did something useful? I get the feeling it must be some kind of kludgy workaround for some historical happenstance that has long since passed...

  • 5
    On one of my laptops, I came to use the numeric keypad with NumLock off in preference to the normal PgUp/PgDn/Home/End keys, simply because they are easier to reach, and I barely get to turn NumLock on to use those keys as an actual numeric keypad. So it's exactly the opposite for me… Jul 1 at 18:48
  • 13
    a time in history I guess I'm a historical figure now. Jul 1 at 19:26
  • 19
    My keyboard has over a hundred keys on it. But there's one labelled "NumLock". Pressing it turns a perfectly good numeric keypad into a superfluous duplicate of the dedicated arrow keys just a few millimeters to the side of it. Obviously, that is an extremely stupid idea. This is backwards. It turns the auxiliary keypad into a useful duplicate of the numeric keys. Seriously - it's called NUMLOCK to lock it into numeric mode (from normal mode) just like CAPSLOCK locks the keyboard into capital-letters mode (from normal mode), Jul 1 at 20:09
  • 8
    @Aganju I am younger than 40 and we used the numpad all the time in university labs to enter in data from a piece of paper. I would use it at work today too if my keyboard had one. Good for whenever you just need to mindlessly enter in number after number. Turns a frustrating error prone 5 minute task into a mindless, accurate 30 second task.
    – DKNguyen
    Jul 2 at 23:48
  • 6
    I'm here to stay.
    – Num Lock
    Jul 4 at 6:45

4 Answers 4


My keyboard has over a hundred keys on it. But there's one labelled "NumLock".

Simply because the dedicated cursor keys were not there to begin with. As seen here with the original PC Model F Keyboard delivered with the PC-XT:

enter image description here

(Picture taken from Wikipedia)

Or more exactly, what we know now as numeric keypad was the cursor keys. Using them as numeric keyboard was a secondary function to be activated with NUM-LOCK. Doing so was considered an optional thing for accountants.

It wasn't until the Model M Keyboard for the PC-AT, in 1986, that IBM added dedicated cursor keys:

enter image description here

(Picture taken from Wikipedia)

Pressing it turns a perfectly good numeric keypad into a superfluous duplicate of the dedicated arrow keys just a few millimeters to the side of it.

To keep compatible with existing software the 'Numeric' Pad was designed exactly like before, except that NUM-LOCK is now engaged by default(*1). The NUM-LOCK LED, usually located in the upper left, should show this. Doing allowed the use of cursor keys and num-pad at the same time without switching.

So when you are now pressing NUM-LOCK, it's disengaged, reverting the key-pad back to its original function, which is exactly the cursor keys.

While NUM-LOCK now may seem useless, it could not be dropped, as some software used it to switch between certain modes. So go at it like with every other key you don't need: ignore it :))

*1 - At least during the 1990s most BIOS had a setup item to select whether the keyboard is to be initialized with NUM_LOCK on or off - on usually being the default selection.

  • 11
    With NumLock off, pressing the "2" key gives KP_Down whereas pressing the dedicated cursor key gives Down. It is possible therefore to map the keypad keys to other uses entirely, for instance some editors.
    – Martin
    Jul 1 at 19:47
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    @Martin: Yup, I spend my working days with an Emacs major mode that does just that. Jul 1 at 20:52
  • 9
    The numpad also allows you to use an 8 direction cursor which includes the diagonals with single key presses. This is useful in some situation, for example in some games. Using any other collection of 8 keys on the keyboard for this scenario is less convenient.
    – quarague
    Jul 2 at 10:55
  • 4
    @Raffzahn The other use for the numpad is to have fast typing of all digits with a single hand similar to what a cashier does. This is also useful in some situations, but OP seems to ask wy their is a cursor option on the numpad although there are regular cursor keys nearby.
    – quarague
    Jul 2 at 11:08
  • 3
    Who needs cursor keys if you have aswd ;-) Jul 4 at 11:00

The NumLock key still exists because some people like the numeric block to act as numbers and others prefer them to have their classic cursor-motion capability. This capability offers an intuitive way to handle the cursor, one that many of us spent years using. Plus many of the cursor control blocks lack a number of the motion commands offered by the numeric keypad.

Some computer and keyboard manufacturers are doing away with NumLock, though. I recently bought an HP desktop that has a numeric keypad, but no NumLock key. Nor was there a function key combo I could find which would allow the numeric keypad to act the way "it should." Fortunately one of the keys became unreliable (w), allowing me to go to Best Buy and get an actual $30 keyboard that not only has NumLock, but the classic "clicky" feel and sound.

  • 11
    You were allowed to get the $30 keyboard before the key failure ;-) Jul 3 at 12:05
  • 1
    @JeopardyTempest, I just couldn't justify it. Yes the keyboard bothered me. Bit it worked and came with the fairly new machine.
    – RichF
    Jul 7 at 3:47
  • @RichF: If you really didn't want to spend $30: Perhaps you could have bought a used keyboard from a thrift shop (e.g. Goodwill) or classified-ads website. Or perhaps you could have bought a refurbished keyboard from a local discount-electronics or surplus-electronics store. Jul 8 at 4:14

Way back in 1978 Digital Equipment Corporation (DEC) introduced the VT100 terminal. This was a market leader at the time and design decisions were to influence the subsequent history of all terminals, keyboards and terminal emulators. The keyboard layout shows many features of subsequent keyboards, though in slightly different locations: enter image description here

(Jason Scott, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons)

The keypad could operate in two modes. As a numeric keypad it could be used for rapid data entry. but DEC published plastic overlays that allowed the keys to be redefined, most commonly as the EDT keypad: enter image description here

At this date normal terminals did not come with mice or graphics pads!

When the VT220 was released in 1982, significant thought went into producing a standard keyboard that was suitable for all users. The result was the LK201: enter image description here

Meanwhile IBM had been starting the PC revolution from 1981, but using its model F keyboard which many users compared unfavourably to the larger DEC keyboard ("toy" and "cramped" for example). DEC maintained strict patent and copyright on the LK201 to try and restrict the market in third party VT220 (and later) clones. IBM took the ideas from the LK201 and used them to produce the model M keyboard in 1985. The keypad was redesigned since it didn't have to comply with EDT (and the subsequent EVE) editor layout. The number of function keys was reduced from 20 to the current 12. A dedicated escape key was added and over the years the number of bottom row buttons has increased. However the lineage is obvious.

Which brings us back to the NumLck issue. It was essential in the pre-mouse days of the early 1980s and 1970s. Keyboards were expensive, between 5 and 10 times the cash cost (not allowing for inflation) of a modern basic keyboard. Anything that could allow keys to "double up" saved significant amounts of money.

  • 1
    While interesting, this feels only indirectly related to the question, because neither of the models shown feature the same cursor key / num pad layout as the Model F, nor a dedicated "Num Lock" key. Really the only connection is "keys doubled up with some kind of mode shift", and even then the DEC terminals seem to have much more of a "soft layout" approach, where it is the application interpreting key sequences, not the keyboard having an extra locking state.
    – IMSoP
    Jul 4 at 11:56
  • No, the model F is not recorded as being inspired by the DEC keyboard, it was the Model M. See en.wikipedia.org/wiki/LK201
    – Martin
    Jul 4 at 15:21
  • I love EVE. It’s much better than vim.
    – RonJohn
    Jul 5 at 0:29
  • "...suitable for all users." Not really. They managed to seriously inconvenience both vi and TECO users with their move of the Esc key, for example (so much that they eventually had to move it back closer to its original location). This was discussed in the media of the time.
    – cjs
    Jul 8 at 0:20
  • Was vi that widely used on DEC machines at that date? I'll accept that TECO was, though personally I've never used it, leaning instead EDT. BTW, your link leads to a Wiki page on "Bit-paired keyboard" which never mentions "ESC". The link from that page to PC-Mag appears to be talking about a model F: "Perhaps the appearance of complexity could have been reduced if there were two key groups on the right - one for numbers and one for the cursor", which of course both the LK201 and Model M did.
    – Martin
    Jul 8 at 10:26

Raffzahn gave a fine, complete answer. Don't mean to compete with any fact or conclusion drawn in it.

As they say, "that said"... There's a little more.

Consider the layout of the arrow keys in the first pic. Well, second too, of course, but the earlier keyboard being more directly to the point as it is earlier in the evolution. Why would the keys be placed as so, up arrow the "8" and so on? Why not "1-2-3-5" (maybe some time traveller influencing something trivial for some fun) or "decimal point-1-3-5" to get a diamond shape that kinda feels pretty natural while the current "one over three" button array does not?

Not a technical expert here so no wonderful list of cool older computers from outside the micro-world will follow. But I did have plenty of experience using my employer's software grafting something of a POS onto a warehouse program and so using equipment in a mixed typing environment, one of numbers and letters with the numbers being a bit more important. Probably a mainframe in the back end as people called it so, but it could have been a mini-computer for all I know.

In any case, the "numberpad" was on the left side of the keyboard, not a physical numberpad, but sharing the QWERTY letter keys. And it was laid out the way the keys are on that first keyboard's (yes, and all 400 billion of them since) physical numberpad.

Anyone who used both navigation AND numberpad aspects, like me, was very used to this layout. It WAS awkward in that most were no more left-handed than I, and I imagine that's part of how it ended up on the right-hand side, not the left (piles of function keys being common on the left being a bigger element in that choice, I further imagine). But that layout, both of numbers and of navigation keys, might have been something they would have thought important to preserve as there was only a shift of hand with the burned in pattern the same.

IBM, in particular, was always a "you get precisely what you pay for... and not an jot more... even when you didn't realize how closely they could slice against that bone" kind of company. Putting extra physical keys on a keyboard costs incrementally more, the same way $5 more for the gas tank of a Ford Pinto would save lives but making a million of them that's $5 million and maybe the lawsuits would come to less so... They keys we have today, versus the 88 they had to start with, came only grudgingly.

Therefore I cannot say as a fact they thought deep in their bones that any numberpad put on the keyboard MUST, just MUST, include navigation ability as well to properly care for their incumbent computer users rather than just being cheap &%#$)'s who were HUGELY grudgingly seeing themselves forced to provide for a numberpad. But I will say it seems a very NATURAL evolutionary move. They were providing a numberpad, grudgingly or not, so why not be brilliant and bring navigation into the game? (Outside just Enter and TAB, that is.)

And one still needed to have a function-style key to do the switching back and forth. Probably was either innovative to have a dedicated key for that guessing it wouldn't be needed too frequently or perhaps just a techspec timeline running out and someone pointing out software folks were owning the function keys there were so maybe they couldn't really use them for it without trouble.

Hence the dedicated NumLock key.

(And believe it or not, ScrollLock was useful once upon a time, and I cry myself to sleep (metaphorically) about having no modern PauseBreak functionality.)

So I will say, for me the preponderance of guess-idence says that's what happened. And it wasn't enough so we got the modern one-over-three set of arrow keys. And the "Home-End-PageUp-PageDown" set as well.

If I am correct, that would be about the lowest level explanation of why they came into existence TOGETHER, not separately and later combined. (And usability would later separate them.) And which I think the poster would be happy to know of as a small point to go with Raffzahn's answer.

Slightly aside, that is also how some of the shortcuts we usually still have access to in software came into being as well. I loved WordStar when entered the PC world (and Locascript in the CP/M world... what that program got out of a dot matrix printer vs. what DOS got for years was incredible). It used a shortcut convention I do not know the name of, but that convention either came from the mainframe/minicomputer world or was powerfully influenced by it because it fit perfectly everything we had to do at that job. I loved WordStar for its functionality and the user's detailed control not for its chosen shortcut convention, but that was nice too. (And yes, my "user's detailed control" was, for 99.99% of people, "I hate it, it doesn't DO anything for you, you have to do every little thing." But you know, potato-pah-tah-toh.) Connection being the left side of the keyboard being used a lot of ways, not so much the right side, though it was also.

So I think someone with more knowledge or technical experience from the time could regress the layout and need for switching even further.

  • What do you mean by the same way $5 more for the gas tank of a Ford Pinto would save lives but making a million of them that's $5 million and maybe the lawsuits would come to less so? I don't understand this line. How would an increase in fuel prices save lives? By people driving less and thus air quality improving, having less lawsuits against Ford for contributing to air pollution? Or do you mean something else?
    – gerrit
    Jul 4 at 8:21
  • Simply: Ford were caught out understanding that the design of the Pinto would cost lives, but calculated that the costs of remedying this exceeded the costs of the lives lost. See en.wikipedia.org/wiki/…
    – Martin
    Jul 4 at 9:05
  • 1
    @gerrit the $5 is not the cost of fuel but the additional cost of manufacturing the car to a design that is less likely to result in fire. Also, adjusting $5 for inflation from the early 1970s to May 2022 using the consumer price index, you get roughly $40 (inflation was high around then, so it varies depending on which year you choose). But according to Wikipedia, the figure was $11 rather than $5, from a 1973 report, so roughly $73 today. Another way of looking at it: the first model started at $1850, of which $11 is roughly 0.6%.
    – phoog
    Jul 4 at 12:54
  • "In any case, the "numberpad" was on the left side of the keyboard, not a physical numberpad, but sharing the QWERTY letter keys." Cool, except, on IBM Hardware (and most other) without a numpad, it was always on the right side (UIO JKL M,.) for numeric overlay. See this for an abbreviated history of numeric entry. POS systems have always been SST developments, thus not really in line with the rest of the industry. It might be helpful to add what kind of environment you're talking about, especially the mainframe an terminal part.
    – Raffzahn
    Jul 6 at 13:54

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