The mirror curves enable us to study B-model topological strings on noncompact toric Calabi-Yau threefolds. One of the method to obtain the mirror curves is to calculate the partition function of the topological string with a single brane. In this paper, we discuss two types of geometries: one is the chain of N P-1's which we call N-chain geometry, the other is the chain of N P-1's with a compactification which we call periodic N-chain geometry. We calculate the partition functions of the open topological strings on these geometries, and obtain the mirror curves and their quantization, which is characterized by (elliptic) hypergeometric difference operator. We also find a relation between the periodic chain and -chain geometries, which implies a possible connection between 5d and 6d gauge theories in the larte N limit.