When Apple Computer Inc signed its string of agreements with IBM Corp a couple of years ago, it appeared that IBM got rights to offer Macintosh System on its own PowerPC-based machines – so that Apple appeared to be paying a very high price for the agreement. Well that may still be the case, but it seems that any such offering IBM comes up with will be a poor relation to the Real Thing from Apple. The company says it has an implementation of the IBM-Motorola Inc PowerPC 601 RISC microprocessor designed specifically for its Mac emulator technology, which leaves IBM – currently the fabricator of all 601s – busy working on its own 601 implementations. The emulator technology is paramount to Apple’s PowerPC strategy, providing interoperability and compatibilty with its Macintosh System 7 and future System 8 operating system and existing Mac applications. At the microprocessor level, Apple’s 601 ROM has been separated from the PowerPC CPU – it sits outside the chip and has had Motorola’s 68000 instruction set embedded into it to translate 68040 instructions into RISC code the 601 can understand. To the rest of the system and to the end user there will be no difference in look and feel to an existing Mac machine, says the firm. But the ROM technology is Apple’s alone, and will not appear with any PowerPC systems from other vendors, says Apple’s PowerPC product manager, Jim Gable. Other PowerPC developers will have to support Mac emulation through PowerOpen, the trio’s AIX-based operating system for the architecture, via products like Insignia Solutions Ltd’s SoftPC and Echo Logic Inc’s emulator. Apple has also done some fancy footwork at the system software layer, providing mixed-mode functionality, enabling applications written via ToolBox, the company’s Mac programming tool, to be transferred back and forth between RISC and complex instruction set environments. To do this, Apple has converted two of its most used tools, QuickDraw and Memory Manager, into RISC code, so applications can run on both architectures. Application performance is not affected, claims Gable. The rest of ToolBox will be re-compiled to RISC code over the next year or so. The first 601-based Macs will be released in January or February next year and will be phased in with the firm’s existing Centris and Quadra server lines. Gable says Apple expects to shift one million units of 601 Macs by the end of the year. The company has no plans to support any other operating system except PowerOpen and says Microsoft Corp’s Windows NT is definitely not on the cards. Meanwhile, silicon schedules for the other PowerPC microprocessors are still on track and it expects the low cost, low energy 603 CPU destined for laptops and notebooks to begin silicon sampling early next year. The mid-range 604 chip should roll out in late 1994 and the symmetric multiprocessing 620 in 1995, the firm says.
