First off, I'll take a keyboard where they key mapping is done with xkb over a keyboard where it's not, almost universally. That, more so than any particular key availability or layout, matters to me. Because of the beautiful simplicity that if you have that, you can set what keys you do have to be much more suitable for you.

Want a tab key? Easy, find some unused key combination (or one used for something you don't care for), and use it. For me, that's Fn+Enter on the N900.

Even on the N900 with its 3-row, rather limited keyboard, I have just about any key I want, the limitation being more about how many key layouts I can memorize and comfortably use. I have Fn+Shift (in that order. Shift+Fn is just another key level in one layout) mapped to cycle through my key mappings. I have the latin/english characters and all the commonly used specials in that layout, cyrillic/russian characters and many other special characters on a second one, and have been in the process of putting together a third layout for all the special characters that typically come up in mathematics or science. I can certainly type more things in at will than is available (near as I can tell, if the only keys available are the ones printed on the buttons) on the N950 keyboard's default key mapping.

Secondly, if the above is satisfied I'm perfectly okay with 3-row keyboards. 4-row and 5 row would also be acceptable to me, thought I would conjecture this would make touch-thumb-typing harder, and 5 seems like pushing it, but if overall it's comfortable to use, great. Bigger keyboards typically mean they start to expand, which means you need bigger and bigger hands to comfortably reach all the keys with your thumbs. This has more to do with the size of the device than the key placement, though. The black-berry Z10, for example, from my fiddling with one, is sometimes noticeably uncomfortable for me because it's size means I actually end up having to 'reach' with my thumbs. I can tolerate it because it doesn't come up often, but I would absolutely hate being thus inconvenienced with a keyboard. (Admittedly, usually on a keyboard you don't have to reach across more than half the span thereof with a given thumb, though depending on exactly what key combinations you've mapped to what, and whether the modifier keys like shift and Fn 'latch' or need to be held to have their effects. On the N900 for example, shift and fn latch, but some programs, like emacs, seem to disregard this latching and then you have to held them pressed down to get the desired characters).

So the point is, I really don't have two much of an ideal layout. It should have arrow keys, and ideally the full set of modifier keys (Ctrl, Shift, Fn, Alt, Meta), although the minimal N900 set (Ctrl, Shift, Fn) has worked well enough for me most of the time. Give me xkb on the software end, and I can take it from there, thanks.

I'm not familiar with the 'xkb in the software end', but what you tell above souds good. Especially if you need to write with a character set of a 2nd or 3rd language, or use a lot of special symbols, it is nice to have a special new layer of your "own" characters. Like you say, memorizing them is a challenge. That's why layout designers and localizers want to stick to some standard conventions, and leave the personal customizing to be done by the user's own wish and responsibility.

Yes, there are many factors which affect the writing ergonomics. And they really need to be tested thoroughly. A "Sliding Qwerty Keyboard Half" will certainly be even more challenging than the existing sliding Qwerty phones, because the "display part" (= the phone) will be a lot heavier than the display part of N900, for example. Text entry is affected a lot by the balance (where is the weight center of the phone + OH combination). which depends on whether there is a battery in the Qwerty, and where exactly. The optimal place for the battery could be below the keymat, but such a place can make the Qwerty OH quite thick. In any case, many tests need to be done. Perhaps also the place of the keymat need to be tested; what is the optimal distance between the leftmost and rightmost keys from the left and right ends of the keyboard.

Below you can see the Qwerty of N950. Like on most HW Qwerties of Nokia it uses three modifier keys which affect characters: Shift, Sym and Fn (on this keyboard using the "north-east arrow" label).


With the Sym key can be entered a wide variety of characters that are used by most European languages. Its operation is different from the corresponding "press and hold a key" function of virtual touch-screen keyboards. But their purpose and character sets are quite similar. On HW Qwerties "multitapping with a key while holding the Sym key despressed" is more complex to use than the corresponding "tap and hold a key and slide onto the wanted variant letter" function of virtual keyboards. But in the case of most European languages, the most frequently used variant letter is there as the default letter on virtual keyboards, and as the "1st letter variant" on HW keyboard, which you get by pressing the Sym and letter key at the same time (or the Sym key a bit earlier). These operations are complicated to explain in writing, but once you've learned to use them, you will not long for any "special character tables", which are still found on some phones. The Fn key is needed for punctuation marks, paretheses, etc symbols which are printed on the keys. For these reasons I recommend keeping both the Fn and Sym keys on the keyboard. The Sym key is essential also for keyboard shortcuts: on smartphones the Sym key could be used like the Alt key of full-size Qwerty keyboards in some keyboard shortcuts, such as Sym+Enter (= Alt+Enter). For the planning of keyboard shortcuts, the standard full-size keyboard is the best reference. Because the simultaneous pressing on three or more keys is too difficult, keyboard shortcuts should be used moderately, or they should be made with "sticky" modifier keys. so that you can make the keyboard shortcut "in series".

The Ctrl key is a must, which often saves us in some difficult situations. For instance, selected text can be cut/copied/pasted with Ctrl+C, Ctrl+X, Ctrl+V, respectively - on web pages there often is no other way to make those operations. On touchscreen you may see corresponding function buttons, but when writing text on a HW keyboard it is usually a lot more practical to use the Ctrl-shortcuts than the Cut / Copy / Paste labels on the touchscreen. Keyboard shortcuts made with arrow keys are very powerful. Because there are no keys like Home, End, PgUp, PgDown, some 3-key shortcuts may be needed.

I have a zenbook. The keys are plastic, not aluminium.The stuff below the keys looks aluminium though.

Ever used n950? As I find it's keyboard inferior to n900 keyboard - space between buttons is too big, shift key is on some strange position, etc. Not to mention the weird way to open it (but I guess this is OT)

EDIT:
not shift but ctrl key

As I say, clam shell preferable!

Can't see how this is OT given the thread title.

Well I have never seen N950 but from the pictures I assume the device opens the same way E7 does.

I had E7 in the past, and while the keyboard is pretty decent to use the problem is exactly opening the device.
You absolutely cannot open it single-handed, and it takes care and force to open it with two hands. The device is so slippery it's easy to drop it when trying to open the keyboard.

I had a clamshell-type-faux-leather device protective cover with my E7, and using that it was easier to open it because you could get some friction between your hands and the device, but without it, --> very difficult.

Yup, it's basically the same kind of mechanism, t'was one of it's biggest criticisms back in the day.

I prefer the straight-sliding keyboards of N810 and N900 for several reasons. One reason: it provides exciting possibilities to replace separate keyboard and camera-grip OHs. Or, the holes of a Sliding Qwerty Half can be used as a lens hood and a lens cover for the camera of Jolla phone. Please see what I wrote to http://talk.maemo.org/showthread.php...27#post1379527

The exact places of the Ctrl and Shift keys seem to vary on N950, depending on localized languages and perhaps also HW versions. To me the keyboard of N950 does not look too bad in picture http://talk.maemo.org/attachment.php...1&d=1379155831
except that its tilting screen mechanism is worse than the straight and less complex construction of N810 and N900. I believe that the Ctrl key was moved to the right-thumb edge to make it easier to make the most common shortcuts of Ctrl+A, Z, X, C, V, B.

Regading your comment "space between buttons is too big", my comment is: what matters most is the shape of the keys, not their exact dimensions. The reason why I don't regard the keys of N950 as ideal is the flatness of the keys. Actually, it is the distance of the tops (centers) of the keys that matters, if their shape is spherical enough.

How about making all keys in a sheet of molded clear transparent plastic, along with a cheap resistive-touch e-paper screen placed underneath the keys, and some led-lighting around it.

That would give a physical keyboard with fully configurable key labels.

The only permanent decision will be the dimensions of the matrix of physical keys, i.e. 3, 4 or 5 rows times 11, 12, 13 or 14 keys, possibly with an extra large key on the bottom row to potentially use for space. If you want cursor keys, sym, ctrl, tab, Fn, esc, alt or any other modifiers will be a user decision depending on the keyboard layout you download, install and display on your keys.

I for one will have a layout that includes pipe, ampersand and all sorts of braces easily accessible :-)

In Internet is found a page where is introduced a transparent, flexible, molded plate which can be put on the screen of a tablet. Just now I can't find it, but you can google or duckduckgo for it. They claim that it is patented