Handover between software and hardware accelerator

A bytecode accelerator which translates stack-based intermediate language (bytecodes) into register-based CPU instructions transfers plural pieces of internal information from a register file of a CPU to the bytecode accelerator by means of an internal transfer bus between the bytecode accelerator and the CPU and an input selection logic of the bytecode accelerator when the bytecode accelerator is started and transfers plural pieces of internal information in the bytecode accelerator to the register file of the CPU by means of the internal transfer bus, an output selector and an output selector selection logic of the bytecode accelerator when the bytecode accelerator ends its operation in transition between hardware processing and software processing by software virtual machine.