SuperH or SH was developed by Hitachi. It is 32-bit reduced instruction set computer. SuperH is implemented by the microcontrollers and microprocessors forembedded systems. Its structure is different than others. The SuperH-4 architecture supports to both big-endian and little-Endean byte ordering.
History of SuperH Introduction
In 1990s, the first SuperH processor core was developed by Hitachi. Hitachi has also developed a complete groups of compatible instruction set CPU cores. The SH-A and SH-2 were used in Sega Satum and Sega 32X. These cores have 16-bit instructions for better code density than 32-bit instructions.
After some years, another SuperH family was also included, that was SuperH-3 CPU family. SuperH-3 was included with some new features and other interrupt concepts , a memory management unit (MMU) and modified cache concept. The SuperH-3 are also have DSP extension, that’s why they are also called SH-3-DSP. They have more data paths to perform better DSP processing, special accumulators and dedicated MAC-type DSP engine. With SH-2 core a derivative was also used.
In the beginning of 2001, Hitachi and ST formed the IP company named SuperH, inc., purpose was to license the SuperH-4 core to other companies and to develop the SuperH-5 architecture. In 2004, SuperH, Inc sold the IP of these CPU cores to Renesas Technology.
The SuperH-5 was introduced later. Its designed supported two modes of operation. SHcomact mode and SHmedia mode. The SHcompact mode is equivalent to the user mode instructions of the SH-4 instruction set and SHmedia mode is too different, it uses 32-bit instruction whth 64-bit integar registers and SIMD instructions. In SuperH-media (SHmedia) mode the destination of a branch is loaded into a branch register separately from the actual branch instruction. This permit to the processor to prefetch instructions for a branch without having to snoop the instruction stream. The combination of compact 16-bit instruction encoding with a powerful 32-bit instruction is not a unique to SuperH-5.
ARM processor have a 16-bit Thumb mode, and MIPS processors have a MIPS-16 mode. However, SuperH-5 differs because its default compatibility mode is 16-bit encoding rather that 32-bit encoding.
Still there is evolution in SuperH-5 architecture. The latest step in evolution of SuperH-5 was happened in 2003 where the cores from SuperH-2 up to SuperH-4 were getting unified into a superscalar ShperH-X core . SuperH-X forms a kind of instruction set superset of the previous architectures.
Today, the SuperH CPU cores, architecture and products are with Renesas Technology, a merger of the Hitachi and Mitsubishi semiconductor groups and the architecture is consolidated around the SH-2, SH-2A, SH-3, SH4 and SH-4A platforms giving a scalable family.
Models of SuperH Microcontroller
There are different Models in SuperH technology. Its evoulution is still in progress.
Main and most used SuperH models are as following.:
- SuperH-1 – used in microcontrollers are used in embedded applications (CD-ROM drives, major appliances, etc.)
- SuperH-2 – used in microcontrollers with high efficiency, speed and accuracy required, these are also used in automotive such asengine control units or in networking applications, and also in video game consoles, like the Sega Saturn. The SuperH-2 are also being used in many motor control applications.
- SuperH-2A – The SH-2A core is an advance shape of the SuperH-2 core. It includes some extra instructions but most importantly moving to a superscalar architecture (It has the ability to executer more than one instructions in one cycle) and two five-stage pipelines. It also incorporates 15 register banks to facilitate an interrupt latency of 6 clock cycles. It is also strong in motor control application but also in multimedia, car audio, power train, automotive body control and office + building automation
- SuperH-DSP – initially developed for the mobile phone market, used later in many consumer applications requiring DSP performance for JPEGcompression etc.
- SuperH-3 – used for mobile and handheld applications such as the Jornada, strong in Windows CE applications and market for many years in the car navigation market
- SuperH-3-DSP – used mainly in multimedia terminals and networking applications, also in printers and fax machines
- SuperH-4 – used whenever high performance is required such as car multimedia terminals, video game consoles, or set-top boxes
- SuperH-5 – used in high-end multimedia applications
- SuperH-X – mainstream core used in various flavours (with/without DSP or FPU unit) in engine control unit, car multimedia equipment, set-top boxes or mobile phones
- SuperH-Mobile – SuperH Mobile Application Processor; designed to offload application processing from the baseband LSI