These MCUs are fabricated using the high-performance silicon gate CMOS process, embedding the R8C/ Tiny Series CPU core, and is packaged in a 20-pin molded-plastic LSSOP, SDIP or a 28-pin plastic molded-HWQFN. It implements sophisticated instructions for a high level of instruction efficiency. With 1 Mbyte of address space, they are capable of executing instructions at high speed. Furthermore, the R8C/1B Group has on-chip data flash ROM (1 KB × 2 blocks). The difference between the R8C/1A Group and R8C/1B Group is only the presence or absence of data flash ROM. Their peripheral functions are the same.