Hitachi Ltd’s SH series of original RISC microprocessors has been hovering in the back ground for a year or three now – we wrote up the version for Personal Digital Assistants back in 1993 (CI No 2,220), but the family is growing fast, and now the basic CPU is available as a core for application-specific parts (CI No 2,702), where it will challenge Advanced RISC Machines Ltd’s ARM. All members of the SH family are based on a processor design that has high on-chip peripheral integration, low power dissipation and uses 16-bit op-codes to minimise system memory needs. SH1, the SH7034, SH7032, SH7021 and SH7020, were designed as embedded controllers and rated at 16 Dhrystones MIPS. SH2, the SH7604, was launched last year and is used by Sega Enterprises Ltd in its Saturn games console as a microprocessor; it’s rated at 25 Dhrystones and has 4Kb of on-board cache. The SH3, comprising the SH7702 and SH7708, were launched earlier this year and are still only sampling; they are rated at 100 Dhrystones, have 8Kb cache and a memory management unit; the chips are being targeted at handheld computers and mobile telephones, among other things. Next year there will be the SH4, running at 300 MIPS and clocked at 200MHz, fabricated in 0.35 geometries and requiring just 2.5V. All members of the family have single cycle execution of basic operations in a five-stage pipeline: the SH1s have a 50nS machine cycle, the SH2s are 35nS, and the SH3s are 16nS.
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