A method and apparatus for optimizing a backup chain using synthetic backups is described. The engine may be one engine of a plurality of engines configured to access a shared memory, and the engine may be configured to receive data from the shared memory or to send data to the shared memory. The film can be a smoke material of the M56 turbo smoke generator to resist the millimeter-wave and infrared wave. The load module is connected with a first power supply terminal, the driving module, the first node and the second node, respectively, and stores the analog data signal in the load module and provides the driving module with the analog data signal under the control of signals from the first node and the second node. The contact region is arranged outside the switch housing.