The MB90550A/550B series is a line of general-purpose, high-performance, 16-bit microcontrollers designed for applications which require high-speed real-time processing, such as industrial machines, OA equipment, and process control systems. While inheriting the AT architecture of the F2MC*-8 family, the instruction set for the MB90550A/550B series incorporates additional instructions for high-level languages, supports extended addressing modes, and contains enhanced multiplication and division instructions as well as a substantial collection of improved bit manipulation instructions. In addition, the MB90550A/550B has an on-chip 32-bit accumulator which enables processing of long-word data. MB90552B and MB90553B are radiation noise decreased type. There are no change in the functional specification.