The Hitachi H8 is a large family of 8-bit, 16-bit and 32-bit microcontrollers made by Renesas Technology, originating in the early 1990s within Hitachi Semiconductor. The original design, the H8/300, was an 8-bit processor that had a 16-bit registers and ALU that allowed some 16-bit operations. Two upgraded versions were introduced, the H8/300L that expanded the instructions to become a full 16-bit machine while being optimized for low cost, and the H8/300H which further expanded the registers to allow 32-bit operations and was optimized for low-power/high-performance roles. Many variations exist.

A microcontroller or microcontroller unit (MCU) is a small computer on a single integrated circuit. A microcontroller contains one or more CPUs along with memory and programmable input/output peripherals. Program memory in the form of NOR flash, OTP ROM or ferroelectric RAM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips.