You will need
  • KVM switch for two or more of the system unit.
Take the KVM switch. It has a socket for incoming signals (video card, keyboard, mouse) which will connect the appropriate device of system units. There are also jacks for outgoing signals, where to connect the monitor, mouse and keyboard.
Connect the KVM switch to the first system unit, connect the corresponding connectors of the video card, mouse and keyboard. Similarly connect the other system unit.
Connect your monitor, keyboard, and mouse to the KVM switch to the connectors labeled Out. Once you have everything connected, turn on the KVM switch. Display switching is done usually by double-clicking on the Num Lock key and the number pad, for example, figure 1 refers to the first system unit, and 2 to the second.