I recently bought a Linksys KVM box to use two computers with the same keyboard, mouse and monitor. Unfortunately it’s second hand and it came without a manual so I don’t know how to switch between the computers. Any hints?

There are a number of KVM switches around (the letters KVM stand for the devices you can hook into these, that is Keyboard, Video and Mouse) and they all use some sort of mechanism to switch from one computer to the other. Some have buttons on the devices themselves, but others will use a particular keypress to effect the switch.

Without knowing the precise device I can’t tell you exactly however here are a few things to try:

• Some use the Scroll Lock button to switch between different computers. Press it twice quickly and press Esc
• Others use the up and down arrow to select which computer to use. Press the Scroll Lock twice then one of the arrow keys

It’s always worth keeping this example in mind when buying second hand kit. Without instructions, some technology can be pretty useless. This applies to complex devices like oscillators, all the way to simple ones like dehumidifiers. Just try making sure you have all the paperwork when you make a new purchase, as it can mean the difference between a useful device and an expensive paperweight.