Usually there are no problems with Linux and the keyboard. Though there are two minor caveats: First the setleds program might not work. Second the key mapping might not fit your needs. Some UNIX users and vi users expect to find the <CONTROL> key to the left of the <A> key. Many PC-type keyboards have the <CAPS-LOCK> key there. You may use xmodmap or loadkeys to re-map the keyboard. Some laptops (e.g., Toshiba) allow you to swap the <CAPS-LOCK> and <CONTROL> keys. Mark Alexander offered this solution in the linux-laptop mailing list: On RedHat, it's a one-line patch to /usr/lib/kbd/keytables/us.map , or whatever file is referenced in /etc/sysconfig/keyboard:
*** us.map~ Tue Oct 31 14:00:07 1995 --- us.map Thu Aug 28 13:36:03 1997 *** 113,119 **** keycode 57 = space space control keycode 57 = nul alt keycode 57 = Meta_space ! keycode 58 = Caps_Lock keycode 59 = F1 F11 Console_13 control keycode 59 = F1 alt keycode 59 = Console_1 --- 113,119 ---- keycode 57 = space space control keycode 57 = nul alt keycode 57 = Meta_space ! keycode 58 = Control keycode 59 = F1 F11 Console_13 control keycode 59 = F1 alt keycode 59 = Console_1
A second (or external) keyboard can be attached using the PS/2 port (I suppose this is not possible via the serial port, since there is no keyboard controller for the serial port). Also there is one laptop with a detachable keyboard the Siemens Scenic Mobile 800. This machine uses an infrared connection to the keyboard, but I don't know whether this works with Linux.
Don't plug the external keyboard in while the laptop is booted, or plug the mouse in the keyboard port and the keyboard in the mouse port. On a Toshiba, this caused one user to have to completely shutdown the laptop, remove the keyboard/mouse, and do a cold reboot.
For PS/2 ports there are so called Y-Cable available, which make it possible to use external mouse and external keyboard at the same time if your laptop supports this feature.
Parport to AUX port adapter In some cases one kbd port and one aux port is not enough and you may want to add another keyboard or mouse. You can use this adapter, together with the parkbd.c module for that.
On some laptops a splitter works to allow both mouse and keyboard to be plugged in; on others it doesn't work at all.If you might want to use both you had better check that it works, or you may find yourself waiting anxiously for USB support.
Sun keyboard to PC serial port adapter: Many people have dreamed having their Sun Type 5 keyboard attached to their Linux box up to now. And with this adapter, it is finally possible. Because the standard Sun keyboards use TTL RS232 at 1200 bps to talk to the Suns, it's very easy to make them talk to any non-Sun computer by converting this to true RS232. All what you need is a MAX232 chip that'll take care about the correct voltage levels, and also some chip to invert the signals (CD4049 in the pic, I've used a 7400 quad-nand myself), since the MAX232 inverts them as well, and we don't need this. This all easily fits into a 25-pin serial connector.