Dynamic Device Mapping (DDM)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/DDM_mapping.jpg/220px-DDM_mapping.jpg)
Dynamic Device Mapping is a robust technology for USB KVM switches implemented to replace standard USB keyboard and mouse emulation.
KVM device emulation
Many USB KVM devices provide peripheral emulation, sending signals to the computers that are not currently selected to simulate a keyboard, mouse and monitor being connected. These are used to avoid problems with machines which may reboot in unattended operation. Peripheral emulation services embedded in the hardware also provides continuous support where computers require constant communication with the peripherals. In addition, some types of computer systems do not treat USB devices as hot-pluggable, which means the keyboard and mouse will not be re-detected when switching back to a particular KVM port. For these types of systems, it is necessary to implement device emulation.
Standard device emulation has it's limitations. When emulating a USB keyboard, mouse, and monitor it is impossible for most KVM's to simulate various different types of I/O devices specifically. As a result, KVM switches will sometimes offer inconsistent performance and even sometimes unsolved compatibility issues with the shared keyboard, mouse, and other devices.
Dynamic Device Mapping (DDM)
With DDM (Dynamic Device Mapping) Technology, the communication between shared devices and all connected systems are maintained 100% of the time, even as a user switches between the KVM ports. This makes generic device emulation unnecessary as the DDM allows each connected computer system to believe all connected I/O devices are remaining connected even as the KVM switch might move to another port.