Apple Ponders NuBus Migration As PCI Prototypes Begin To Circulate

By Theo Gantos, CCP

(August 5th 1994)

Apple was showing off its next generation PCI machines in closed session at the MacWorld Expo in Boston this week, and a few prototype machines are already circulating, equipped with 100MHz 601 processors. Following its earlier technology demo, David Limp, Power Macintosh product manager, confirmed that the machines, due early in 1995, will initially use the 601 in speeds up to 120MHz.

Apple will adopt the full PCI 2.0 specification, including Open Firmware which allows cards to operate independently of OS implementation. However, the PCI cards will also need a driver for System 7.5 (or Apple Unix) to be usable on the new machines. Apple says it is developing its own PCI bridge chip, so it is making some aggressive projections concerning throughputs. PCI is designed to run at 132MB/sec compared with between 10-33MB/sec for NuBus. Apple sees PCI as an enabling technology for new applications that need high bandwidth such as video conferencing and editing, ATM, and enterprise servers.

NuBus card migration is still up in the air, and Mr. Limp is hesitant to discuss details, except to say that Apple will try to accommodate customers with investments in existing cards. He admits that engineering such a migration path is proving difficult. The problems apparently stem from difficulty in adapting NuBus signals and latencies to PCI timings.

PowerPC News is an electronic journal published in London, UK

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