A KVM switch (with KVM being an abbreviation for "keyboard, video and mouse") is a hardware device that allows a user to control multiple computers from one or more sets of keyboards, video monitors, and mice. Although multiple computers are connected to the KVM, typically a smaller number of computers can be controlled at any given time. Modern devices have also added the ability to share other peripherals like USB devices and audio.
Before the mouse became relevant in server switching applications, the term Keyboard Video Switch (KVS) was used to describe keyboard and monitor switching devices. With the increased adoption of Microsoft Windows, the mouse and other I/O ports in peripheral switching became prevalent. Remigius Shatas, the founder of Cybex (a popular peripheral switch manufacturer at that time) expanded the initialism to Keyboard, Video and Mouse (KVM) in 1995. Some years later, Universal Serial Bus (USB) began to become the new industry standard for connecting computer peripherals.
As a result of the growing need to switch peripherals (such as touchscreens) in addition to the keyboard, mouse and monitor, some companies are now selling "KVMP" switch devices (standing for keyboard, video, mouse and peripheral).
A KVM Switch is a hardware device, used in data centers, that allows the control of multiple computers from a single keyboard, monitor and mouse (KVM). This switch then allows data center personnel to connect to any server in the rack. A common example of home use is to enable the use of the full-size keyboard, mouse and monitor of the home PC with a portable device such as a laptop, tablet PC or PDA, or a computer using a different operating system.
KVM switches offer different methods of connecting the computers. Depending on the product, the switch may present native connectors on the device where standard keyboard, monitor and mouse cables can be attached. Another method to have a single DB25 or similar connector that aggregated connections at the switch with three independent keyboard, monitor and mouse cables to the computers. Subsequently, these were replaced by a special KVM cable which combined the keyboard, video and mouse cables in a single wrapped extension cable. The advantage of the last approach is in the reduction of the number of cables between the KVM switch and connected computers. The disadvantage is the cost of these cables.
The method of switching from one computer to another depends on the switch. The original peripheral switches (Rose, circa 1988) used a rotary switch while active electronic switches (Cybex, circa 1990) used push buttons on the KVM device. In both cases, the KVM aligns operation between different computers and the users' keyboard, monitor and mouse (user console).
In 1992-1993, Cybex Corporation engineered keyboard hot-key commands. Today, most KVMs are controlled through non-invasive hot-key commands (e.g. Ctrl+Ctrl, Scroll Lock+Scroll Lock and the Print Screen keys). Hot-key switching is often complemented with an on-screen display system that displays a list of connected computers.
KVM switches differ in the number of computers that can be connected. Traditional switching configurations range from 2 to 64 possible computers attached to a single device. Enterprise-grade devices interconnected via daisy-chained and/or cascaded methods can support a total of 512 computers equally accessed by any given user console.
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F.A.Q. about KVM switch
What is KVM?
KVM is an abbreviation for Keyboard (keyboard), Video (video) and Mouse (mouse), which connect to computer ports. KVM products connected to various ports transmit or switch computer signals.
Consequently, KVM is a designation of a group of technologies, not special brands or companies.
What is KVM technology?
The acronym KVM means keyboard, video, and mouse, and refers to computer ports. KVM equipment connects to these and other ports, from where computer signals expand or switch. In this way, KVM stands for technology, not a brand or a company.
Who needs KVM?
KVM products can be used by anyone using computers.
KVM products are used for:
- Noise reduction. Ability to move computers from radio studios.
- Save space. Ability to move computers from an air traffic control tower.
- Protect computers from damage. The ability to move computers from the test room to a secure server room.
- Create more ergonomic consoles. The ability to avoid heat generation by moving computers.
- Reduce the number of peripherals. Ability to control multiple computers using one monitor, keyboard and mouse.
- Simplification of administration. The ability to facilitate maintenance and administration of computers by moving to a central server room.
- Create flexible working concepts. The ability for users to access the computer (s) from various consoles.
What is a KVM switch?
The KVM switch connects several computers that can be controlled from a single console (monitor, keyboard, mouse).
Switching between computers is carried out through the button on the switch or using hotkeys. Depending on size, KVM switches also support OSD technology for switching between computers.
For example, Guntermann & Druck offers KVM switches for DVI and VGA signals that allow the user to control from two to 64 computers.
What is a KVM transmitter?
The KVM transmitter transmits keyboard, video, and mouse signals to control the computer remotely.
Each KVM transmission system consists of a transmitter and a receiver. The transmitter connects to the computer keyboard, video, and mouse interfaces, while the receiver connects to a remote console. Both devices are connected by one or more cables.
Various suppliers offer KVM transmitters for DVI and VGA signals, which use CAT cable (“twisted pair”) or optical fiber for transmission. Signals such as audio, RS-232, USB 1.1 or USB 2.0 can also be transmitted.
What do I need to work with KVM switches?
Different KVM switches have different requirements. In most cases, all you need is a KVM switch, the required number of cables to connect all your computers, keyboard, monitor and mouse, and, in fact, the computers themselves. This is the basic configuration; more complex systems may require more components.
What is a matrix KVM switch?
The matrix KVM switch combines multiple transmitters and switches in one device.
Multiple consoles can access multiple computers - even over long distances. Systems are mainly divided by the type of video signal transmitted. Matrix KVM switches are available for expanding DVI, VGA and other signal signals.
In addition, matrix switchers are divided into compact devices (specific device characteristics, such as the G&D CompactCenter) and modular systems (such as the G&D DVICenter).
Why are some KVM switches so much cheaper than others?
As with all products, some of them have more options. Certain switches offer equipment sharing via USB, On-Screen Display (OSD), audio support, emulation ports, multi-platform capabilities, built-in converters, and shipped with cables and power supplies. You decide whether you need these options or not.
What is an OSD?
OSD, short for On-Screen Display, is a graphical representation of computers connected to the KVM switch, allowing you to select the computer you want without pressing the buttons on the KVM switch or using hotkeys. If you have a multi-user switch, this function can also show you which computer each user currently has access to.
What is a video splitter?
The video splitter allows you to split the VGA/DVI signal and display it on multiple monitors. This product also has several options. You can send these signals via a CAT5 cable or a standard VGA cable. You also have the option of transferring audio for multimedia applications.
What is a remote reboot?
Remote reboot allows you to reboot servers from anywhere in the world using the Internet. You can do this with a simple web browser.