Advanced Micro Devices Inc and Cyrix Corp realise they need to do more than simply offer clones of Intel Corp microprocessors if they are to justify their place in the iAPX-86-compatible market, and they have joined forces to come up with what Compaq Computer Corp regards as a superior interrupt control system for symmetric multiprocessing than Intel Corp’s 8259 interrupt controller standard. Called the OpenPIC – Programmable Interrupt Controller – specification and code-named Sundance, it defines an architecture for sharing out work over multiple processors. Compaq helped define the standard, which challenges the Intel APIC Advanced Programmable Interrupt Controller standard used in dual-processor Pentium systems. Apple Computer Inc, Motorola Inc and IBM Corp’s PowerPC and Microelectronics groups are also expected to endorse the standard. OpenPIC supports as many as 32 processors and is designed to support all current iAPX-86 products and the PowerPC. Intel’s P54C Pentiums have an integrated APIC that can support as many as 60 processors; the APIC architecture requires a system to include a single input-output APIC as well as an integrated APIC on each processor, where the OpenPIC spec calls for using independent caches for each processor. In Peripheral Component Interconnect-based systems, Advanced Micro and Cyrix propose a Centralised Interrupt Controller chip that supports the OpenPIC architecture features and register set. The specification is offered free; chip set maker Opti Inc and BIOS king Phoenix Technologies Ltd will implement it.
