A Secure keyboard-mouse switch apparatus comprising: a user keyboard port capable of interfacing with a user keyboard; a keyboard host emulator (27, 44) to emulate a computer host; a user mouse port to connect a standard user mouse or pointing device; a mouse host emulator (26, 45) to emulate a computer host; a plurality of host peripheral port means (32a, 32b,... 34a, 34b,... 15a, 15b...) for coupling to respective computers through cables; a plurality of device emulator means (37a, 37b,... 38a, 38b,... 48a, 48b,...) each to emulate, to a computer coupled via a respective host peripheral port means, either (a) a keyboard and a mouse or (b) a composite device having a keyboard and a mouse; channel select switch means (35, 36, 41, 50, 55, 70) to couple only one selected device emulator means at a time to the keyboard host emulator and the mouse host emulator; at least one unidirectional flow forcing circuitry (39a, 39b,... 40a, 40b,... 46a, 46b,...) to assure that data flows only from the host emulators to the device emulator means and no data flows from the device emulator means back to the host emulators; and a System Controller function (28, 45) to control said channel select switch means based on user inputs, the keyboard host emulator being coupled between the user keyboard port and the channel select switch means and the mouse host emulator being coupled between the user mouse port and the channel select switch means, characterised in that the System Controller function is capable of operating in cursor tracking mode wherein channel select is extracted from mouse cursor position and path analysis compared to pre-programmed displays arrangement to provide the user with the visual illusion of a single continuous desktop workspace across different isolated displays (2a, 2b,...) coupled to corresponding isolated computers (6a, 6b,...). a user keyboard port capable of interfacing with a user keyboard; a keyboard host emulator (27, 44) to emulate a computer host; a user mouse port to connect a standard user mouse or pointing device; a mouse host emulator (26, 45) to emulate a computer host; a plurality of host peripheral port means (32a, 32b,... 34a, 34b,... 15a, 15b...) for coupling to respective computers through cables; a plurality of device emulator means (37a, 37b,... 38a, 38b,... 48a, 48b,...) each to emulate, to a computer coupled via a respective host peripheral port means, either (a) a keyboard and a mouse or (b) a composite device having a keyboard and a mouse; channel select switch means (35, 36, 41, 50, 55, 70) to couple only one selected device emulator means at a time to the keyboard host emulator and the mouse host emulator; at least one unidirectional flow forcing circuitry (39a, 39b,... 40a, 40b,... 46a, 46b,...) to assure that data flows only from the host emulators to the device emulator means and no data flows from the device emulator means back to the host emulators; and a System Controller function (28, 45) to control said channel select switch means based on user inputs, the keyboard host emulator being coupled between the user keyboard port and the channel select switch means and the mouse host emulator being coupled between the user mouse port and the channel select switch means, characterised in that the System Controller function is capable of operating in cursor tracking mode wherein channel select is extracted from mouse cursor position and path analysis compared to pre-programmed displays arrangement to provide the user with the visual illusion of a single continuous desktop workspace across different isolated displays (2a, 2b,...) coupled to corresponding isolated computers (6a, 6b,...).