This paper proposes embedding 256 Kb resistive random-access memory (ReRAM) in a microcontroller unit as a data buffer for communicating with a stand-alone flash memory. In this study, the chip was manufactured using a combination of the TSMC 0.18 mu m process and the Industrial Technology Research Institute ReRAM back-end-of-line process. The ReRAM was equipped with a novel sense amplifier that had three magnification times for the reference cell current for increasing the read yield by 32%. Furthermore, the ReRAM controller included built-in self-test, built-in self-repair, a shortened Bose-Chaudhuri-Hocquenghem (99, 64, 5) error-correlating code, and asymmetric coding can yield ReRAM up to approximately 100%. When compared with the conventional dynamic random-access memory (DRAM) buffer, the proposed architecture reduces the system execution time by 25% and the power consumption by 15% at 25 MHz. Simulations also showed that the ReRAM buffering runs at least 51% faster when compared with the use of other nonvolatile memories such as ferroelectric RAM, phase change RAM, and conduct-bridge RAM. Although ReRAM buffering is just competitive in speed and power consumption of spin-transfer torque magnetorresistive RAM buffering, ReRAM has clear advantages in area, cost, and reliability.