Keyboard, Video, Mouse

In this video I will look at KVM’s. KVM’s allow you to control multiple computers using a single keyboard and mouse. This video will look at how you can use a KVM to save you money and space.

Download the PDF handout: http://itfreetraining.com/handouts/ap...

Keyboard Video Mouse (KVM)
0:12 KVM or Keyboard, Video, Mouse, does as the name suggests. It takes a keyboard, monitor and mouse and connects them to multiple computers. To understand how this works, consider that I have three different servers.

In order to use these servers, we need a keyboard and mouse to supply input, and a monitor to see the output. In a server room where space is limited, you probably don’t have the room to install extra keyboards, monitors and mice. This is particularly true when you have a server room that may have hundreds of servers in them. Consider the cost of having a separate keyboard, mouse and monitor for each server. Also, consider that once a server is setup, except for the occasional maintenance, you will probably rarely control the server by using the keyboard and mouse. Thus, the cost of supplying individual keyboards, monitors and mice is hard to justify.

This is where a KVM comes into play. In this example, the three servers are connected to the same KVM. At any one time, one server is connected to the keyboard, video and mouse. To change this, press the button, usually at the front of the KVM, to select which computer you want. Some KVMs may change the computer being used by you pressing a key sequence on the keyboard.

Let’s have a closer look at how a KVM works.

Mechanical KVM
1:37 The first KVMs were essentially a mechanical switch – the switch redirected the wires between each computer to the one common keyboard, monitor and mouse. These KVMs are essentially obsolete nowadays. The problem with these KVMs is that each time the switch is turned it essentially disconnects one set of wires and connects another set.

Disconnecting one set of wires and connecting another set caused all kinds of problems. For example, some computers would need to detect the keyboard and mouse when the computer started up. If the computer did not detect the keyboard and mouse, they may be disabled. This essentially means that when the computer is switched on, it would need to be selected on the KVM.

Other problems could also occur, particularly with the video when starting up. If the switch was not set to that computer, the computer would not be able to detect the video and may change the video resolution.

Other problems occurred when the switch was changed; the disruption in the connection could cause the keyboard, video or mouse to stop working. The reliability of the KVM would vary depending on its quality. This became more of a problem as video resolutions increased, so you can see why this kind of KVM is obsolete nowadays, but it illustrates the basic principal of how a KVM works. You can also understand why a KVM may also be called a KVM switch.

Basic PS/2 KVM
3:04 The next KVM that I will look at is a PS/2 KVM. This particular type of KVM takes two computers and allows them to be plugged into the one keyboard, video and mouse. It is just a matter of plugging each of the plugs into each computer and then plugging the keyboard video and mouse into the KVM.

Nowadays, you probably won’t be using a PS/2 KVM, as the technology is pretty old. However, it does demonstrate the basics of a KVM in which you plug in your keyboard, video or mouse so it can be shared between your computers.

These KVMs use electronics to change which computer is selected, rather than switching wires. The electronics will emulate a keyboard, video and mouse, so when the computer is starting up it will think it is connected to one, even when it is not selected on the KVM. Some KVMs, however, either do a poor job of emulating or don’t do it at all. If you have one of these KVMs, you may still need to have the KVM selected when you switch the computer on.

This shows the basic features; however, some KVMs come with more features.

Description to long for YouTube. Please see the following link for the rest of the description http://itfreetraining.com/ap/1d20

References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 3 Position 13238-13355
“CompTIA A+ Certification exam guide. Tenth edition” Pages 410 – 412
“KVM switch” https://en.wikipedia.org/wiki/KVM_switch
“File:Data Transfer Switch - video and keyboard-8613.jpg” https://commons.wikimedia.org/wiki/Fi...

Credits
Trainer: Austin Mason http://itfreetraining.com
Voice Talent: HP Lewis http://hplewis.com
Quality Assurance: Brett Batson http://www.pbb-proofreading.uk