Integrated Device Technology Inc, Santa Clara, California has added a 133MHz version of its Orion R4600 RISC microprocessor. The R4600 Orion implementation of the MIPS Technologies Inc architecture is claimed to be the first processor to bring together the combination of very high performance, dynamic power management, and low price for Windows NT and high-end embedded applications and offers much better than Pentium performance at less than 80486DX prices. The R4600 is a full 64-bit implementation of the MIPS III instruction set architecture but uses a shorter internal pipeline – five stages rather than eight – resulting in fewer stalls and, therefore, higher performance. The R4600 contains the best primary cache available in any MIPS processor – 16Kb for instructions and 16Kb for data, using a write-back protocol and two-way set-associativity. It also looks as if the company’s strategy of manufacturing chips before full characterisation was finished has paid off. That’s a calculated risk where the first handful of layers are processed, maybe 60% or so of the total work, and the wafers are stored while the company finishes designing the rest of the part, the really critical layers. The result is reckoned to cut a month or more off time-to-market. Comparing the new part with the PowerPC, the company highlights the fact that it already runs Windows NT, whereas PowerPC still has nine to 18 months of effort to be at the same level – and offers a 1.5 times price-performance advantage, and a 53% absolute performance advantage over the 66MHz PowerPC 601. A FlexBus software initialisation mechanism on the Orion 4600 enables designers to choose their own bus interface frequency – the internal clock frequency can be divided by 2, 3, 4, 5, 6, 7 and 8. Since a simple bit-stream initialises the chosen mode, designers can use the same board for a range of price-performance solutions, only changing the programming of a low cost serial EEPROM to fix the bus frequency on each board. The 133MHz version is sampling now with volume to start this month, at $370 for 10,000-up. The parts currently require a 5 Volt power supply, but 3.3V versions are planned.
