About: Agent 005 of the Graffiti Research Lab

Double your productivity by connecting a single keyboard to two computers! It's simple: one keyboard, two USB connections, infinite possibilities. Each finger stroke will be twice as powerful with this keyboard mod. This is a low cost, no soldering, HOW TO that will double your key strokes per hour in minutes.

To complete the double computing system see also the DOUBLE MOUSE tutorial.


Part: Keyboard (USB)
Vendor: Radio Shack
Cost: $14.99 or less
Notes: You only really need one keyboard but you need two serial cables. I ended up just buying an extra keyvoard because at RadioShack they are cheaper then a serial cable. Any old keyboard will do, both USB or PS/2 will work, check This example uses a USB keyboard, PS/2 keyboards will also work see the DOUBLE MOUSE post.

Part: QVS USB-PS2Y USB to Dual PS/2 "Y" Converter
Vendor: J&R
Cost: $14.99
Notes: You are going to need two of these. There are cheaper options but this is the only one that I know works for sure.

Part: Duct tape
Vendor: Any will do.

Tools: A sharp Xacto blade and/or wire cutters.


- Cut one keyboard cable at the midpoint.

- Cut the second keyboard cable an inch or so away from the keyboard. This keyboard is no longer needed, hide it in a drawer for later use.

- You should now be left with one longer serial cable, one shorter serial cable, and one keyboard. Cut away 1.25" of the outer cable from the ends of all three cables.


Inside the serial cable you will find smaller red, black, white, and green cables. Cut away 3/4" of the outer rubber and twist the exposed copper for each of the individual 12 cables.


Twist together groups of three wires consisting of the same color. Tightly wrap them in tape so that none of the copper is showing.

Yes, I know taping the connections is totally ghetto. I have since bought a soldering iron, but I will also say that this taped version has been working for over a year and half, and has survived several moves. LONG LIVE SOLDER FREE DIY!


Once all four groups of red, white, black, and green wires are wrapped together tightly wrap them all in tape. When you're done you should have a dirt style Y cable.


Step 1:
Most USB keyboards come with a basic USB to PS/2 adapter, if not you can get them here for $3.99. Plug this adapter onto the end of your USB keyboard (effectively giving you a PS/2 keyboard).

Step 2:
Now plug the USB to PS/2 adapter into the PS/2 to USB adapter. I know this sounds silly, but Instructables member Grendel tells us that the larger PS/2 to USB cables interpret the PS/2 signal, reformat the data into USB HID packets, and send them on to the PC. Normally you can't have 2 USB Hosts on the same bus but this hack gets around that.

Step 3:
Plug in one of the USB connections into a PC. When you have the keyboard functionality properly then plug the other USB connection into another PC. If everything goes as planned then you should now have the power of two PC's at the tip of your fingers.... use this power wisely.

Step 7: USES?

I'm curious to see if anyone finds any "practical" uses for this. It could be used to control multiple World Of Warcraft characters (of course there are also software hacks for this). I used the Double Keyboard and Double Mouse for an installation in collaboration with Aram Bartholl called Web 2.0 (URL coming soon). Project description, images, and wanky video listed below:

Project Description:
Web 2.0 is a gallery installation consisting of two internet enabled computers, a hacked mouse and keyboard, and a custom plugin for the popular (and free) Fire Fox web browser. Two computers are connected to a single keyboard and mouse allowing visitors to control both identical machines at the same time while using just a single input device. The only difference between the two internet terminals is their network connection; one machine is connected to the less restricted internet in Hong Kong, while the other is connected to the internet through a connection point in the mainland of China.




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    44 Discussions

    Hi, I tried this out but it didn't work. The keyboard lights come up briefly and then after that the keyboard does not work. Has anyone been able to replicate this and get this to work??

    i have created the above keyboard which works on 2 PC at same time, it is sending same command.

    But unfortunately it is not working properly,

    e.g:- started with all letter in in caps but after some time , one of the system is typing in caps and another one in small.

    Please help me if any one has experienced the same issue or kind of similar issue with above solution

    you can program 2 computers at once.

    I think the best practical use is from M. Gyver so far - configuring new machines. Multi boxing in wow could work I guess, if you are the same class, right?

    I use one keyboard and one mouse ps2 on extension cables plugged into a ps2 to usb converter then usb pluged into kvm four pc usb cluster to ccontrol four pc . there are two usb hubs on the kvm i plug in the one usb there. as far as the coumputers it eliminates all the mouse and keyboard pluging and un pluging just presss button. easy to install each pc has two usb ports in back used by keyboard and mouse. but on mine that leaves on or two left up front

    The four port ubs based kvm switch cost me fifty dollars but i have not been staning on my head under the desh lately as much. and when i pull a tower to add pci devives its just unplug three wires power ,and two usb then case comes out to disconnect video i guess thats four. i bought two two port
    kvm switches never used thereon amazon please buy them !!!! lol


    Yeah Like
    christophski says:
    why? just use Synergy. or KVM switch but for the hack of it nice done!

    if you had two identical machines could you use this like a back up ... that way you have atleast 2 copies of everything ? great instructable

     I thought this was a great instructable. I love the idea. But I thought it was absolutely useless, until now. I assume that a switch (kinda like a floor switch for a lamp (you know ... one you stand on)) can be added (somewhere along the line) so that you can change from one computer to the other. Then I wouldn't have all this clutter on my desktop. Sometimes I'm working on 3 computers (rarely, but sometimes. mostly just 2) and the clutter is crazy. What do you think? Me? I wouldn't even know where to start!

    1 reply

    What you need is a KVM and they are thankfully readily available just about everywhere.
    For a mere $20 -
    Here's one for PS2:
    and one for USB:

    and tons more here of varying quality and prices (some w/ audio, etc),+Adapters+&+Switchboxes/Switchboxes/KVM+Switches/

    I just use Remote Desktop, i can then keep all 6 computers busy from 1 mouse 1 keyboard 2 screens. (just a thought) you guys keep up the good work.

    I used to have 2 computers in my room with two sepearate things 2 mice, 2 keyboards, two monitors, & 2 CPU's this would be pratical for looking on the internet on both computers at the same b/c with two mice and keyboards this could be very confusing.

    2 replies

    You are essentially still doing the same thing on both the computers. Ifyou have both the computers on, then since both receive the same info,you are just doing the same thing on both the computers

    I might make this for a friend as a cheap keylogger.  One plugs into a closed laptop with a word doc open and the other one goes into the victim's computer.

    2 replies

    True, but it's meant only as a temporary way to get a password, in my case