AFAIK you can connect as many keyboards as you have USB ports. And more with hubs (but mind the 500mA limitation when using passive hubs)

With some software/driver hacking I'm sure you could go as high as the USB adressing space allows 😀

Just two keyboards are more than plenty. Need one for normal standard input, and I need one for the homemade keyboard-encoder.
Just a small mame project, wich have been going on and off the past +6 years.

So basically what the KeyRah does (usb based C64 matrix keyboard to PC keyboard adapter)?

You can defnitely connect multiple keyboards. How the OS will handle it is another story.
In most cases, it will treat all the keyboards as one and without a special driver, it wouldn't be possible to separate one keyboard from another.

shock__ wrote:

So basically what the KeyRah does (usb based C64 matrix keyboard to PC keyboard adapter)?

Not quite, yet the same in some way.
Have seen it been done on youtube.

I've had two or even three "keyboards" connected at once. Keep in mind that a keyboard is not a keyboard but a HID device, so...

- My keyboard (obviously) is a keyboard, but it's also a soundcard.
- Some mouses can act as a mouse+keyboard device (for some special buttons).
- My USB earphones act as a keyboard (with four keys... "volume up", "volume down", "mic mute" and "mute all").

Also some devices have drivers that can emulate keyboard, like a Logitech G13 or a Saitek Cyborg Command, so you may end with some fake keyboards connected.

IME hooking up 2-3 standard keyboards is no problem via USB, nor has PS/2 + USB been a problem. Where it becomes weird is if one (or more) of the keyboards have special software suites + extension buttons. For example if you have a generic keyboard and a fancy Logitech keyboard with the Logitech software. Windows will treat them all as the "same" keyboard, but the Logitech software may not want to start or may behave in unpredictable ways with both keyboards connected. Alternately if you had two different Logitech models that can use the same software, things may behave oddly. Note that I'm just using "Logitech" as an example - I'm not saying specifically Logitech will or won't work for what you want. And of course I've never seen a "fancy" keyboard that has extra software that absolutely requires that software for normal functionality - it's usually just to enable extra buttons like media controls, macro keys, etc.

The same goes for mice in my experience as well.

My main rig (Windows 7 32 bit) have two keyboards and two mice connected to it at all times, for the last 4-5 years. I have a MS Sidewinder X6(?) keyboard and an X4(?) mouse directly connected, and a simpler USB MS keyboard and another USB MS mouse (explorer?) connected thru KVM switch. The simpler keyboard and mouse has no special features, but Sidewinders' has some and everything works without a glitch (MS software installed).

This youtube video made me want to do some usb-hacking and asking about how many usb-keyboards a pc can handle.

https://www.youtube.com/watch?v=RUGYbLtfAiE

I seem to recall a utility for preventing unexpected USB keyboards, as this is one form of attack from a compromised USB device.
https://www.gdatasoftware.com/en-usb-keyboard-guard

You should be able to connect 127 of them without too much trouble.

I have a wireless numpad in the center of my steering wheel to give me more buttons

AllUrBaseRBelong2Us wrote:

You should be able to connect 127 of them without too much trouble.

🤣 - good one. That's the limit of the specification, so... 😀

Reminds me of the story of the USB Cart of Death.
http://blogs.msdn.com/b/oldnewthing/archive/2 … 064.aspx#197468