A command processor determines whether a command descriptor describing a current command is in a first format or in a second format, wherein the first format includes a source memory address pointing to a memory area in a shared memory having a binary code to be accessed according to direct memory access (DMA) scheme, and the second format includes one or more object indices, a respective one of the one or more object indices indicating an object in an object database. If the command descriptor describing the current command is in the second format, the command processor converts a format of the command descriptor to the first format, generates one or more task descriptors describing neural network model tasks based on the command descriptor in the first format, and distributes the one or more task descriptors to the one or more neural processors.