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.
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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!

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wolf1128 months ago

you can program 2 computers at once.

mmorpgs1 year ago
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
Helenmelwin2 years ago
Connections of the ps2 to usb adapter is important like that your way of article is also. Thanks mate, let me try it.
alienjoe1233 years ago
dcnigma3 years ago
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
Skidoodles5 years ago
 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!
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/
TRSDOS3 years ago
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.
bwpatton15 years ago
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.
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
late reply. Couldn't you make a switch like mentioned above then switch between the two computers?
Replicator4 years ago
kvm or double usb adaptor would be easier.
KVM all the way. Easier and Safer...
Khord5 years ago
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.
srilyk Khord5 years ago
 cheap and big. Very big.
Khord srilyk5 years ago
True, but it's meant only as a temporary way to get a password, in my case
toogers Khord4 years ago
you could use a pocket PC and some sort of adapter, i guess
Hardware keyloggers are usually cheaper than a laptop, but I see where you're going.

Issue is that it could be very obvious, and there are far easier ways to grab or hack passwords. Such as the freeware known as Ophcrack.

Use this info at your own discretion, however.
Grey_Wolfe4 years ago
With a toggle switch for quickly 'tabbing' between machines this would be a brilliant idea.

Without, you really aren't increasing productivity, as anything you type one one machine could be readily copied and transferred in seconds.

However, this does have multi-boxing applications assuming the machines have similar latency.

WoW players rejoice??? lol
Agroking4 years ago
 ooooooooooor you could download synergykm.
cotton4 years ago
 i see one issue keyboard and mosue are geting TOOOOOO much power cut one of the connecters power.... or make it have a 5 volt regulator so u dont over load it and fry it XP
chrwei5 years ago
add a 2 or 3 position switch so you can choose which PC gets the input and you got 1/3 of an almost free KVM for the "control 2 PC's" thing, there's software for repeating commands to multiple servers via ssh for doing maintenance tasks, so this is like a hardware version of that
You dont even need a software to run the same command on multipleservers, a simple batch script can do that. But this is just not thesame thing. I mean this allows you to type and everything without havingto do anything else, using ssh you are just sending commands nothingelse :)
Zerocool8185 years ago
would this work backwards as in two keyboards on one computer??? plz respond asap
(removed by author or community request)
I had 4 USB mice and a PS/2 mouse hooked into my computer all at once to see which ran smoothest/I liked best, was quite fun
(removed by author or community request)
Ahahahahaha, Evil. Smooth man. I dont mind dictatorships, cause i aint in them and i can admire they're power from over here (AUSfag)
grundisimo5 years ago
Since it is a USB keyboard and you are trying to plug it into a USB slot couldn't you just plug straight into your computer without the converter thing.
You could do that, but the keyboard would only work on one machine at a time. With this hack, you can plug one keyboard into two different computers at the same time such that both machines receive the exact same keyboard input at the same time. This can be useful when testing two different machines and you want to ensure that each is receiving the exact same input. USB won't allow a device to be connected to multiple hosts, but a PS/2 device will work in this sort of configuration. By using the USB-->PS/2 adapter, you are hacking around the USB "single-host" limitation. This is a hack and there are undoubtedly many downsides to this method, but for the writer's purposes (see the last step) it seems to work rather well. I would suspect that you wouldn't need the PS/2-->USB cable if the machine had a PS/2 port that you could plug the keyboard into.
????????????? i am confusled
For this Instructable, the converters are necessary. The goal of this 'ible was to use one keyboard to control two machines simultaneously, and this is only possible when using the USB-->PS/2 and PS/2-->USB adapters. The keyboard would work without the adapters, but you would only be able to plug it into one computer at a time (which defeats the point of this project).
I am still a little bit confused but okay if you say so!
I'll put it this way. It is essentially a ps2 keyboard right? Computer dont mind sending multiply signals for a ps2 keyboard. However, it is infact a usb keyboard to start. This is only because we know which wires are which, but a usb will not send multiply signals and would end in a clusterduck.
grundisimo5 years ago
go onto the internet with one and microsoft word with the other and it will make a weird story thing
M. Gyver6 years ago
I can think of one very practical use for this. Part of my job is configuring multiple identical machines. There are daily instances where having multiple pc's connected so a single keyboard/mouse setup would shave a few minutes off the total time, and ensure that all the machines are identical. When I first realized this I tried to simply splice the green and white wires into an extra USB connection, but it just froze anytime I plugged in the second machine. I never would have known about bypassing it with PS/2.
Nameless376 years ago
Another good use for this could be modding a switch on the mouse to switch in between to computers side by side same with a keyboard
xlnc6 years ago
lol why not jus buy a kvm switch comes under £10 for a decent one i got mine 7 years back n still going strong
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