An apparatus comprising neural processors, a command processor, and a shared memory is provided. The command processor, in response to receiving a context start signal indicating a start of a context of a neural network model from a host system, directly accesses a memory in the host system to read command stream data for the neural network model. The command processor selects a current command and determines whether the current command is a branch command or a command describing neural network model tasks. The command processor selects a command among commands in the command stream data as a next command to be executed, based on a determination on whether the current command is the branch command or the command describing neural network model tasks.