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1990-1995: Platform Crisis: The Tentacles of Legacy
The Mac’s shared graphics model meant it would be non trivial to solve the lack of memory protection for applications. That made it possible for third party applications and extensions to accidently overwrite memory used by the system or other applications, causing fatal system crashes and general instability.
Similarly, there was no simple way to tack on preemptive multitasking. If an application stalled or ran into an unrecoverable error, the system had no way to authoritatively stop it and safely hand control over to another application.
Apple could bolt preemption on the side, but it would be of no use to users of existing applications; app would all need to be entirely redesigned to take advantage of the feature. Major system components such as QuickTime would also need to be completely overhauled, a huge effort that would take years to complete.
PowerPC Hardware
Despite the increasingly creaky underpinnings of the Mac System Software, Apple was able to update the Mac hardware and jettison a lot of architectural legacy in the process when it jumped to PowerPC.
Legacy Hardware Decisions for PowerPC
The partners involved in PowerPC not only designed a new processor, but drew up plans for a reference platform for new PC hardware using the chip. The initial revision was called PReP, the PowerPC Reference Platform.
Ironically, this design incorporated much of the old legacy cruft of the existing x86 PC, including the 1970’s era Centronics parallel printer port. Apple in particular wanted the PowerPC platform to be more Mac-like, rather than a regression back into the old and outdated standards embraced by the PC industry.
PowerPC and CHRP were intended to solve legacy hardware issues for the PC industry, but instead, both were largely ignored because of legacy issues. Apart from Apple, no manufacturer had the power or the vision to offer anything new.
Apple Slowly Ditches Legacy Hardware
By the time CEO John Sculley was ousted from Apple in 1993, the company had to support a range of Mac models, each with a unique hardware architecture, and sold under an array of marketing names, including Performa, Centris, and Quadra.
Sculley had hoped to create a lineup of Macs models with names that sounded like Sony products or luxury cars, but the plan instead created confusion. What’s the difference between a Quadra 630 and a Performa 630? It wasn’t obvious for consumers.
After Sculley’s departure, steps were taken to simplify both marketing and hardware designs. The first generation of Apple’s PowerPC Macs were largely just old Macs with a new processor; the existing product lineup of the 68k based Quadra 610/700/800 became the PowerMac 6100/7100/8100.
In 1995 Apple launched the second generation of PowerMacs, which began incorporating modern hardware conventions of the newest PCs, including PCI expansion slots.
PCs using ISA required manual and often problematic configuration of IRQ lines, I/O addresses, and DMA channels whenever a new device was installed. Mac users didn’t even need to know what an IRQ was.
NuBus had made Mac expansion cards far more elegant to use, but also more expensive to buy than the simpler but more troublesome ISA cards. Apple was able to immediately move its Macs to PCI and instantly create a shared market for PCI cards that could be used in both Macs and new PCs. NuBus was dropped entirely.
On the PC, support for PCI was added to motherboards next to ISA slots so users could have the worst of both worlds: IRQ management headaches from the 80s, paired with a splintered market for the new PCI cards. After all, if all PCs have ISA slots, but only the newest ones have PCI, why not continue to manufacture ISA devices?
More Decisive Changes
The Two Edged Sword of Legacy
Conversely, embracing legacy had helped to keep Microsoft alive. While often used as a derogatory word in technology, the other side of legacy is compatibility and the market power of an installed base.
Microsoft developed its platform using legacy as a key strategy. Rather than initially delivering an elite, expensive solution that required new hardware, Microsoft sold Windows to existing DOS users.
Microsoft frequently compromised ongoing Windows development to bend over backward to support existing DOS and 16-bit software. It provided support for a broad range of hardware, including old outdated interfaces that still represented the majority of what people were actually using in the PC world.
Dueling Business Models
That difference between Apple and Microsoft is not just a philosophical stance, but reflects the two companies’ differing business models:
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Microsoft has become the same lazy dinosaur that Apple had turned into in the early 90s.
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