A method for supporting a plurality of host computers isolation in a system that comprises: a first user display, user peripheral devices such as a keyboard and a mouse, and a secure KVM device, comprising: a controller function; a plurality of first (12aa, 12ba, 12 ca, 12da) video inputs for a plurality of hosts; and a first display video port coupled to the first user display; characterised by a plurality of first Display Plug and Play Emulated Memory, DPPEM, devices, each assigned for one corresponding host, the method (700, 800) comprising: performing preparation sequence comprising the steps of: - reading (704, 804) display Plug and Play data from the first display (2, 2a) by the controller function (20, 1020, 1120, 1320, 1620, 2320, 4620) in the KVM device; - switching (705, 805) the plurality of first DPPEM devices in the KVM device to connect to said controller function; - writing (707, 807) display Plug and Play data into the plurality of first DPPEM devices; - switching (708, 808) the DPPEM devices to hosts to enable host reading of said written display Plug and Play data from said DPPEM devices; and entering normal mode by repeating the steps of: - waiting (709,809) for user selection of a host channel; and, - when detecting a selection, coupling (712, 812) the selected host to the corresponding DPPEM device, user display and user peripherals. a first user display, user peripheral devices such as a keyboard and a mouse, and a secure KVM device, comprising: a controller function; a plurality of first (12aa, 12ba, 12 ca, 12da) video inputs for a plurality of hosts; and a first display video port coupled to the first user display; a controller function; a plurality of first (12aa, 12ba, 12 ca, 12da) video inputs for a plurality of hosts; and a first display video port coupled to the first user display; characterised by a plurality of first Display Plug and Play Emulated Memory, DPPEM, devices, each assigned for one corresponding host, the method (700, 800) comprising: performing preparation sequence comprising the steps of: - reading (704, 804) display Plug and Play data from the first display (2, 2a) by the controller function (20, 1020, 1120, 1320, 1620, 2320, 4620) in the KVM device; - switching (705, 805) the plurality of first DPPEM devices in the KVM device to connect to said controller function; - writing (707, 807) display Plug and Play data into the plurality of first DPPEM devices; - switching (708, 808) the DPPEM devices to hosts to enable host reading of said written display Plug and Play data from said DPPEM devices; and performing preparation sequence comprising the steps of: - reading (704, 804) display Plug and Play data from the first display (2, 2a) by the controller function (20, 1020, 1120, 1320, 1620, 2320, 4620) in the KVM device; - switching (705, 805) the plurality of first DPPEM devices in the KVM device to connect to said controller function; - writing (707, 807) display Plug and Play data into the plurality of first DPPEM devices; - switching (708, 808) the DPPEM devices to hosts to enable host reading of said written display Plug and Play data from said DPPEM devices; - reading (704, 804) display Plug and Play data from the first display (2, 2a) by the controller function (20, 1020, 1120, 1320, 1620, 2320, 4620) in the KVM device; - switching (705, 805) the plurality of first DPPEM devices in the KVM device to connect to said controller function; - writing (707, 807) display Plug and Play data into the plurality of first DPPEM devices; - switching (708, 808) the DPPEM devices to hosts to enable host reading of said written display Plug and Play data from said DPPEM devices; entering normal mode by repeating the steps of: - waiting (709,809) for user selection of a host channel; and, - when detecting a selection, coupling (712, 812) the selected host to the corresponding DPPEM device, user display and user peripherals. - waiting (709,809) for user selection of a host channel; and, - when detecting a selection, coupling (712, 812) the selected host to the corresponding DPPEM device, user display and user peripherals.