H8 Family

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Hitachi H8/323

H8 is the name of a large family of 8-bit, 16-bit and 32-bit microcontrollers made by Renesas Technology, originating in the early 1990s within Hitachi Semiconductor and still evolving as of 2006.[needs update] The family of largely CISC machines is unrelated to the higher-performance SuperH family of 32-bit RISC-like microcontrollers.

It is supported in the Linux kernel since version 4.2.[1]


Subfamilies include the 8/16-bit H8/300 and H8/500, the 16/32-bit H8/300H and H8S and the 32-bit H8SX series, each with dozens of different variants, varying by speed, selection of built-in peripherals such as timers and serial ports, and amounts of ROM, flash memory and RAM. Built-in ROM and flash memory tends to range from 16 KB to 1024 KB, and RAM from 512 B to 512 KB.

The basic architecture of the H8 is patterned after the DEC PDP-11 architecture, with eight 16-bit registers (the H8/300H and H8S have an additional bank of eight 16-bit registers), and a variety of addressing modes. Unlike the PDP-11 however, the H8 architecture employs big-endian byte ordering.

Both H8/300H and H8S have eight 32-bit registers, each of which can be treated as one 32-bit register, two 16-bit registers, or two 8-bit registers, with the H8S having an internal 32-bit configuration.[2] Several companies provide compilers for the H8 family, and there is a complete GCC port, including a simulator. There are also various hardware emulators available.

The family is continued with the H8SX 32-bit controllers.


H8S may be found in digital cameras, some ThinkPad notebooks,[3][4] printer controllers, smart cards, chess computers, music synthesizers[5] and in various automotive subsystems. The LEGO Mindstorms RCX, an advanced robot toy/educational tool, uses the H8/300. Namco employed an H8/3002 as a sound processor for various games it made in the late 1990s: notably those using its System 12 architecture.

In popular culture[edit]

H8 is referenced in the Muse song "Space Dementia".[6]


External links[edit]