I have an old IBM F122. A 122-key keyboard is pretty much peak keyboard when it comes to easily purchased commercial offerings. The smaller less sturdy sibling of the F122, the M122 (yes, M as in model M) can still be purchased relatively easy, but then you lose about a kilo of weight, nicer switches and N-key rollover. The prices for model F keyboards are bonkers today though.
Your option when it comes to a lot of keys (as the one posted here) is either to build it yourself or try to find some very specific offerings, maybe aimed at video production.
It's fairly easy to buy a "multimedia" European keyboard with 124 keys. It's somewhat harder, outwith Brazil, to get hold of a "multimidia" ABNT2 keyboard with 126 or more keys, but they are commercially available there, at least.
Of course! I was never a fan of those flimsy hard plastic keys, so I didn't include them in the peak keyboard. This is more my taste: https://i.redd.it/hkb7kvqpob431.jpg
There is a guy making "new" model F keyboards out there, and if he ever makes an f122 clone I will probably buy it, regardless of price.
Look out for PS2 and a hard requirement to program them via a real PS2 (not a USB emulated port).
I've bought one (cherry switches sans keycaps), filled it with blank keycaps and now I need to put together some electronics to make it useful (it looks like it uses something like SPI internally).
But first, I'm stuck trying to remember why I thought it would be cool. Because it's just an 8x16 grid of switches.
At least that hybrid model with QWERTY has aplausable use case. But mine is just a grid. As for mine, there's only so many shortcuts you can assign to 128 anonymous keys...
As a Tunisian (north africa) I write mixed texts containing both arabic and latin scripts. I have an azerty/arabic keyboard, arabic letters are on the same keys as latin letters so I constantly need to switch layout when I'm typing. A ~200ish keys keyboard would be Ideal for me. And i suppose it's the same for all non-latin keyboards
> Even Latin, if you use enough languages with enough diacriticals. Or want to code in APL. Or use Greek letters when typing math.
I've always wanted something like the space cadet keyboard with a couple of extra modifier keys vs. what's typically available today for typing unusual characters (and the keycaps for making that easy).
That's pretty straightforward to DIY with the TMK firmware. Or even just with Autohotkey and your existing board; pick a key you don't use much (Caps Lock, right-Win, etc) and make it one of your meta keys.
Print your own keycap labels with Avery sheets for starters, and once you've got the layout nailed down, you can send off to have custom caps made by whatever process you like.
Only 3 extra modifiers, really (a PC keyboard having 4, discounting left and right variants) and fewer actual keys (a mere 100) than an old U.S. 101-key Model M keyboard, let alone a modern U.S. 104-key Windows keyboard.
Keyboard maps are on the host, not on the keyboard. Engravings on the keytops are meaningless and are not what determine how a key is understood. A (for example) U.K. 105-key keyboard and a French 105-key keyboard just look like two 105-key keyboards with all the same keys to the host.
Several common operating systems just combine all keyboard input from multiple plugged-in keyboards into one giant "union" keyboard and apply a single keyboard map to it.
I've been working on Linux/BSD software that allows individual different keyboard maps per keyboard, for my user-space virtual terminal system. It's achievable, but I've not encountered anyone else who has seriously attempted to make such a thing work, in the general case where arbitrary USB keyboards can be plugged in and out at runtime.
You're right, I haven't tried this. But my (unmentioned) approach was going to include using at least one fully programmable keyboard -- QMK or similar -- to send precisely the keycodes wanted.
It doesn't work that way. The USB HID usages (and PS/2 scancodes) are the same. There is one usage for the key at (say) D01, and the keyboard doesn't know or control whether it is "Q" or "A" or something else entirely. You cannot switch layouts on the keyboard, because the maps are on the host. Multiple keyboards with D01 engraved with different symbols will not actually vary anything, and all send the same thing across the wire.
Maybe not for 450 keys (!), but I would dearly love to be able to type all the diacritical marks and at least select Unicode ranges (Cyrillic and Greek).
It's been a really low-priority desire (I won't dignify it with "need") and so I haven't even really worked out a layout or even carefully defined what I'd like, but yeah, the Really Big Keyboard would fill at least a small need.
In A.I. War (book by Daniel Keys Moran), Trent uses a "custom 240-point Unicode board" to code in SuperLISP, which originally put the idea in my head. I asked Moran about this. He made it up whole cloth. No such keyboard exists. Of course, we still have ample time to invent one before the time of that story.
If you persuade your operating system to load up keyboard maps with the ISO 9995 common secondary group, you will get all of the combining diacritical marks at least. They're mostly on level 3 of group 2.
Your option when it comes to a lot of keys (as the one posted here) is either to build it yourself or try to find some very specific offerings, maybe aimed at video production.