The problem of generating memory interfaces between loop-based accelerators and external memory is gaining the attention from the high-level synthesis research community. This paper presents an external memory system for inserting/extracting data to/from a loop-based accelerator derived by a high-level synthesis approach. The memory system is composed by four architectural cases which could occur during hardware synthesis. The memory system is based on a global asynchronous local synchronous approach and the use of dualport memory banks. FPGA-based implementation results show that the proposed memory system is technologically achievable and provides a high-bandwidth without introducing communication overhead.