Phase5

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Phase5 Digital Products was a computer hardware manufacturer that made boards for the Amiga computer. Their most well known products were accelerator boards which replaced the CPU with a faster model. Mostly these used a CPU from the Motorola 68k series, but their latest products, the BlizzardPPC and CyberstormPPC, included a PowerPC CPU, along with either a 68040 or 68060 with both CPUs sharing the system address space.

These PowerPC boards operated in a novel fashion where the on board 68k CPU could operate concurrently with the PowerPC CPU. This architecture was enforced by the fact that AmigaOS was 68k based and the required emulation software had not yet been developed to run natively on the PowerPC architeture. This design suffered from the need to flush CPU caches between context switches from 68k and PowerPC code and vice versa, making mixing code ad hoc and often impractical. Minimising these context switches and making mixed binaries required a large amount of effort and planning, making their use somewhat unpopular.

Phase5 developed a PowerPC kernel called PowerUP which ran alongside the 68k based AmigaOS. Effectively, a programmer could then utilise the PowerPC CPU as a coprocessor. German company Haage & Partner developed a competing multi-tasking kernel called WarpOS for the phase5 PowerPC boards which operated in a similar manner but was not code compatible with PowerUP.

Despite planned newer PowerPC boards based on the G3, the company went out of business in 2000, after an announcement on July 22nd, 1999 with QNX Software Systems that they intended to build an alternative to the official Amiga solution of the time, to be known as AMIRAGE K2 [1].

The most common current reference to Phase5 is in the Linux port to APUS computer systems. Phase5 PowerPC boards are also able to run AmigaOS 4 and MorphOS.

Much of Phase5's skills and experience were retained in a new company, bPlan GmbH, which in partnership with Genesi produced the Pegasos, a final realisation of several attempts to build an alternative Amiga system.

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