KVM switch

Lore & Background

The earliest name for such a switch was Keyboard Video Switch (KVS). With the advent of the mouse, the name Keyboard, Video and Mouse (KVM) switch became popular, introduced by Remigius Shatas, founder of Cybex (now Vertiv), in 1995. Some companies call their switches Keyboard, Video, Mouse and Peripheral (KVMP).

KVM switches are categorized by how they handle USB human interface devices. USB hub-based (enumerated) switches require full USB re-enumeration each time the switch changes target, similar to physically unplugging and replugging the device. Emulated USB KVM switches use dedicated console ports to emulate generic keyboard and mouse features, enabling instantaneous switching and hotkey control, but supporting only basic functions. Semi-DDM USB KVM switches work with all USB-HID devices but do not maintain device presence to all computers simultaneously. DDM (Dynamic Device Mapping) USB KVM switches emulate the true characteristics of connected devices to all computers at once, supporting extra function keys, wheels, and buttons.

Switching methods have evolved from rotary switches (Rose, circa 1988) to push buttons on active electronic switches (Cybex, circa 1990). In 1992–1993, Cybex Corporation engineered keyboard hot-key commands, now often complemented with an on-screen display. KVM switches may present native connectors or use a single DB25 connector with separate cables, later replaced by combined KVM cables. Video connectors include VGA, HDMI, DisplayPort, and DVI, with VGA still common in industrial applications.

Reader's Guide

The KVM switch is significant for enabling efficient control of multiple computers from a single console, reducing hardware clutter and improving workflow in data centers and home offices. Its legacy includes the evolution from simple rotary switches to sophisticated DDM-class devices that support high-resolution and high-refresh-rate monitors, such as 4K at 144 Hz, 5K at 120/240 Hz, and 8K at 60 Hz with DSC. The switch handles monitor identification via DDC and EDID in various ways: none (system assumes generic monitor), fake (switch generates its own EDID), or pass-through (attempts transparent communication, but may generate Hot Plug Detect events or fail to pass monitor power states). The COVID pandemic increased demand for KVM switches with built-in docking stations, allowing sharing of I/O devices between a personal PC and a work laptop. The technology continues to adapt to modern gaming and high-end display requirements, with advanced DDM-class DisplayPort 1.4 KVM switches leading the market.

Did You Know?

• The earliest name for such a device was Keyboard Video Switch (KVS).
• Enterprise-grade KVM switches can support over 1,000 devices via daisy-chaining and cascading.