Motorola Inc has revealed further details of its G4 generation four PowerPC chip, which will include support for the 162 new AltiVec graphics instructions it first talked about earlier this year (CI No 3,406). The 32-bit G4 combines the AltiVec instructions with a 128-bit memory subsystem, and is aimed at both the desktop systems – read Apple Computer Corp – and embedded markets. A 400MHz version with 2Mb level two cache and I00MHz system bus is now sampling. Motorola says it has booted up the first operating systems onto the chip and expects production quantities by the middle of next year. The design goals of G4 were to boost bandwidth capabilities, floating point performance and symmetrical multiprocessing support on the same sub-100mm square die size. Power consumption remains under 10 Watts. The chip includes a separate execution unit and 128-bit register file for the AltiVec instructions. So while overall performance is likely to be only around 10% up on the G3 running at the same clock speed, floating point performance will get an estimated 50% performance boost. The chip will be the first to use Motorola’s 0.20 micron HIP5 copper interconnect technology. Learning from Intel Corp’s mistakes with MMX, Motorola and third party companies are providing development tools for AltiVec. An Apple software development kit is available now, and Metrowerks Inc is providing support in the Fall release of its CodeWarrier compilers. Other ISVs are expected to announce support for the instructions next year. Apple itself hasn’t explicitly said it will use the parts for its future Macs, but given its focus on multimedia and IBM Corp’s greater interest these days in the embedded systems market for PowerPCs, it seems very likely to do so.
