This page shows the roadmap of the product group for RX general purpose. The RX660 is a general-purpose MCU supporting 5V power supplies and it is the successor to the RX210. RX231 is the successor to RX210, but RX231 can not replace RX210 as RX231 does not have more than 100 pins and 512kB memory. However, the RX660 can replace the RX210 easily as it is functionally and pin-compatible with general-purpose products such as the RX651 and RX130.