They are typically constructed to fit into a 19-inch rack although there are manufacturers who offer a KVM that can be mounted to a flat surface such as a control console.
With the introduction of the LCD computer monitor, it became possible to combine the display with the keyboard and pointing device into a 1U, 2U or 3U rackmount form factor to create the KVM.
Input signals can be anything supported by the installed LCD controller and includes, but is not limited to, VGA, DVI-D, DVI-I, HDMI, Display Port, Video (Composite, HD-SDI) and so forth.
The form factor will also support non-traditional video and keyboard/mouse signals such as KVM over IP, depending on the installed control circuitry.
Output from the keyboard and pointing device can be either PS/2 or USB, or both, or can be routed through KVM over IP or similar technology.
Due to width limitations of a 19-inch rack (approximately 17.75" between the inside rails), the largest LCD to be incorporated into a KVM was 20.1" with a 3:4 aspect ratio.
It had been previously reported that LG, the last manufacturer for this form factor display, announced the product was End Of Life (EOL) in 2013.