In all the excitement of the Mac's 20th anniversary, another turning point in Apple's history has been overlooked. It's now 10 years since the first Power Mac – which was launched on March 14, 1994. The transition from Motorola's 680x0 chips to PowerPC was a shift nearly as challenging for Apple's engineers as from OS 9 to OS X.

The 680x0 chip family was fast running out of steam, especially in the face of Intel's 8086 technology that dominated the PC industry.

In 1991 Apple showed its in-development object-oriented Mac OS code-named Pink running on an IBM PC. The two former enemies signed a letter of intent, with IBM pledging to help develop Pink and give Apple a licence to its PowerPC processor.

Taking a RISC PowerPC was a RISC (Reduced Instruction Set Computing) processor. RISC technology allowed a chip to be more efficient than Intel and Motorola's CISC (Complex Instruction Set Computing) by carrying only those instructions that are most commonly used. CISC required its engineers to continually add more and more transistors to make each new generation of processor faster. In theory, RISC would still be going long after CISC chips became so overloaded that wouldn't fit inside anything smaller than a shed. (In hindsight, Intel's declaration that it could pack more punch into its CISC chips has proved to be true.)

PowerPC was based on IBM's Power technology for servers and industrial-strength workstations, so the early-1994 deadline wasn't unreasonable. Fred Forsyth, Apple's head of manufacturing and hardware engineering, demanded a launch date of January 24 – to mark the Mac's tenth anniversary. But the software engineers thought October more likely. In the end they compromised on March.

Apple rejected the chance to entirely rebuild the Mac OS to run natively with the PowerPC chip, which would have dramatically increased software performance but wouldn't have run existing Mac software. Instead the OS was to be tweaked so that only the critical 10 per cent of the code would be native, and the rest would be ancient 680x0 code.

Power rangers The hero of the day was a brilliant software engineer called Gary Davidian, who successfully mixed the two types of code and developed it in such a way that older Mac software could run in emulation on the new chip. Davidian and his team worked day and night to provide the first-ever Mac on PowerPC demonstration on October 27, 1992.

Another hero in the story of PowerPC development was a tiny Canadian company called Metrowerks. Though a combination of ineptitude and technical arrogance, Apple's plan to create a cross-platform framework for software development was a disaster. Metrowerks' CodeWarrior revolutionized PowerPC application development.

In a demo to Apple execs in Montreal a Metrowerks employee started to build a program using Symantec's PowerPC recompiler. At the same time a colleague began travelling to the meeting from his home in Boston. He arrived there three hours and 15 minutes later, as the build using Symantec was still grinding away. One minute and 50 seconds later he'd finished his build using CodeWarrior. Without CodeWarrior there wouldn't have been over a hundred PowerPC-optimized programs available within three months of the Power Mac's launch.

Let battle commence The arrival of PowerPC was the real start of the Chip War that would quickly mutate into the Megahertz War. Apple, IBM and Motorola laid into Intel by demeaning its old-fashioned CISC architecture, claiming that RISC was the only way forward in the long term. At 1993's November Comdex show in Las Vegas, the forthcoming PowerPC was seen to blow away Intel's forthcoming Pentium in demonstrations.

In 1994 the first months of the PowerPC proved that the switch was vital to Apple's future. It was, as then CEO Michael Spindler declared, a "quantum leap forward". Even Bill Gates appeared at the launch – although via an overhead screen to save him from the boos and tomatoes.

Within the first two weeks of its March 14 launch, Apple shipped 145,000 Power Macs. Apple ended up shipping more personal computers in the US during the third quarter of 1994 than any other company, knocking Compaq off the top-spot.

The full article on the 10th anniversary of the PowerPC appears in the May issue of Macworld UK - on-sale at newsstands from March 25.