Whether you are administering several Server Boxes, or running a Distributed Computing network, you will always be pressed for space and money. Having 4, 8 or even 16 monitors to watch over is not only inconvenient, but they take up a large amount of room and make a sizeable hole in your budget, purchase cost wise and for power used to run them all. The spaghetti cable syndrome can be a hair pulling exercise when it comes to disconnecting one of them, or worse, keeps tripping you up when entering the room.
Enter the KVM switch.

KVM switches, short for Keyboard/Video/Mouse, allow you to plug one Monitor/Mouse/Keyboard into several computers, depending on the model of KVM. The first models that appeared where manual units that had a big switch you manipulated to select each computer. As a mechanical object, they were prone to wear and tear, and could send a spike down the cables and destroy or damage one of the three peripherals. As technology progressed, KVM technology entered the automatic age, with microprocessor controlled switching allowing anything from simple switching to built in menus with mouse and keyboard emulation modes. Depending on your needs, Automatic KVM switches can be found in 2, 4,8 and 16 port varieties, and some allow daisy chaining to allow up to 255 computer. Adding to the choice among KVMs, you can select simple switching control, models which bring up on screen menus to select different functions, and now the high end units come with built-in LCD displays. Finally, the latest innovation is SOHO KVMs that come with Audio switching allowing you to have full sound available on all the computers. KVMs can support Serial.

THe KVM switch that I use is among the most common in Australia, and comes from a local Company called Serverlink. This company manufactures what many recognize as the highest quality KVMs, servicing not only the Professional market, but also home and small business. Their range includes SOHO, Infinity ( SOHO with Onscreen Display), Standard and High Density Slim line. The last two have LCD displays and come in 1 U Server Rack Form Factor. They slide out with the screen popping up to reveal a keyboard and glide pad.

The model I have is a SOHO 4 Port KVM, the SL-451 It is available with and without cables. Buying the Unit bundles with 4 cables saves you at least $40, as good quality cable sets are $35 each.

As you can see, the cables are a fully integrated unit avoiding the tangle if 3 separate cables were used. Cables come in 2M, 3M, 5M, 10m and 15M lengths, giving good access to computers in dark corners of the room. The unit itself has dimensions of W 210mm x D 70mm x H 50mm , and consumes 2.5 Watts via the keyboard input.

The front panel has 4 lights showing which computer is selected, a Select button for swapping between Computers and a Power light. The left hand side has a recessed reset button for restoring defaults. Moving around to the back, we have 5 sets of ports. One set is to plugh your Monoitor/Keboard/Mouse into, the other four are to connect your computers into the KVM unit. They are colour coded and numbered.

Besides manual control, the 4 computers can be accessed via keyboard commands. The Print Screen Key is used to select between computers. By pressing the Hot key (Left Control key), you enter Command Mode, allow you to assign the Hot Key, change Mouse Emulation Modes, reset Keyboard Driver, swap between computers and enter Scan Mode. Scan Mode continually scans each computer attached to the KVM, allowing you to keep an eye on all computers without having to manually select each one. The default time bertween scans is 2 seconds, not much time to see what is happening on the screen, so you can also select 10 and 20 second scan intervals.
　

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