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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Step 1: MATERIALS / PARTS LIST

IMG_3458.JPG
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 ebay.com. 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.

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mmorpgs says: Mar 21, 2013. 11:34 PM
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?
agentry1 says: Nov 25, 2012. 6:30 PM
Check this out and it's free. I love it.
http://www.microsoft.com/en-us/download/details.aspx?id=27589

Mouse without Borders is a product that makes you the captain of your computer fleet by allowing you to control up to four computers from a single mouse and keyboard.
rapidprototyping says: Jun 27, 2012. 12:26 PM
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
Helenmelwin says: Apr 20, 2012. 2:17 AM
Connections of the ps2 to usb adapter is important like that your way of article is also. Thanks mate, let me try it.
alienjoe123 says: Dec 7, 2011. 5:27 AM
YOU COULD PLAY COUNTERSTRIKE SOURCE TWICE AT ONCE!
dcnigma says: Oct 16, 2011. 2:16 PM
Yeah Like
christophski says:
why? just use Synergy. or KVM switch but for the hack of it nice done!
straightjacket says: Jun 10, 2011. 8:16 AM
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
Skidoodles says: Dec 14, 2009. 8:00 AM
 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!
staida says: May 29, 2011. 2:29 PM
What you need is a KVM and they are thankfully readily available just about everywhere.
For a mere $20 -
Here's one for PS2: http://www.frys.com/product/3975328#detailed
and one for USB: http://www.frys.com/product/5503430#detailed

and tons more here of varying quality and prices (some w/ audio, etc)
http://www.frys.com/category/Outpost/PCtab/Cables,+Adapters+&+Switchboxes/Switchboxes/KVM+Switches/
TRSDOS says: May 29, 2011. 1:39 PM
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.
bwpatton1 says: Feb 26, 2009. 2:13 PM
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.
DrCoolSanta says: Oct 15, 2009. 2:47 AM
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
furrysalamander says: May 27, 2011. 9:46 AM
late reply. Couldn't you make a switch like mentioned above then switch between the two computers?
Replicator says: Aug 12, 2010. 3:24 PM
kvm or double usb adaptor would be easier.
your_dragon113 says: May 5, 2011. 7:11 PM
KVM all the way. Easier and Safer...
Grey_Wolfe says: May 23, 2010. 8:28 PM
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
Khord says: Oct 13, 2009. 5:41 PM
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.
Grey_Wolfe says: May 23, 2010. 8:24 PM
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.
srilyk says: Dec 7, 2009. 10:18 AM
 cheap and big. Very big.
Khord says: Dec 7, 2009. 4:19 PM
True, but it's meant only as a temporary way to get a password, in my case
toogers says: Sep 12, 2010. 6:09 PM
you could use a pocket PC and some sort of adapter, i guess
Agroking says: Jan 11, 2010. 8:33 AM
 ooooooooooor you could download synergykm.
cotton says: Dec 31, 2009. 6:10 PM
 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
chrwei says: Sep 11, 2009. 6:40 AM
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
DrCoolSanta says: Oct 15, 2009. 2:43 AM
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 :)
Zerocool818 says: Jul 13, 2009. 11:02 PM
would this work backwards as in two keyboards on one computer??? plz respond asap
DELETED_Robert L says: Aug 19, 2009. 10:15 AM
(removed by author or community request)
whyexactly says: Sep 11, 2009. 9:35 AM
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
grundisimo says: Jun 1, 2009. 4:04 PM
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.
sparkchaser says: Jun 22, 2009. 1:35 PM
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.
grundisimo says: Jul 6, 2009. 6:16 AM
????????????? i am confusled
sparkchaser says: Jul 6, 2009. 1:34 PM
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).
grundisimo says: Jul 7, 2009. 7:35 AM
I am still a little bit confused but okay if you say so!
Lance Mt. says: Sep 9, 2009. 3:10 AM
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.
theonlypersonherewithabrain says: Jan 22, 2009. 4:34 AM
(removed by author or community request)
Lance Mt. says: Sep 9, 2009. 3:12 AM
Ahahahahaha, Evil. Smooth man. I dont mind dictatorships, cause i aint in them and i can admire they're power from over here (AUSfag)
grundisimo says: Apr 4, 2009. 1:35 PM
go onto the internet with one and microsoft word with the other and it will make a weird story thing
M. Gyver says: Nov 4, 2008. 4:39 PM
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.
Nameless37 says: Oct 7, 2008. 12:56 PM
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
xlnc says: Sep 30, 2008. 12:45 PM
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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