I must go.
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I must go.
Someone out there needs to hear about the IBM PC/AT at this very moment.
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Elias Mårtensonreplied to M. The Crystalline Entity last edited by
@maddiefuzz I thought I knew about it. However, given your post tgere ia clearly more I need to know. Please post more.
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Jason Lefkowitzreplied to Elias Mårtenson last edited by
@loke @maddiefuzz It's probably not what Maddie was referring to, but the AT fascinates me because it is the rare device that was so successful it doomed the company.
The AT used Intel's 286 processor. The 286 was the first x86 processor to offer "protected mode," where the system gives applications virtual memory addresses. This lets it keep applications from poking around in each others' memory. This is a critical feature for multitasking.
But 286 protected mode had a hitch: the chip could switch into protected mode, but not OUT. If you wanted to get out, you had to reboot the whole machine.
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Jason Lefkowitzreplied to Jason Lefkowitz last edited by
@loke @maddiefuzz This was a problem, because the market was full of DOS software that all expected to be able to poke into any memory location it wanted to. So if you had one protected-mode app and 20 DOS apps, owning a 286 would be a pain. Constant rebooting.
Intel fixed this in the next chip, the 386. That one could switch back and forth between modes at will.
But IBM had sold a bazillion ATs to Fortune 500 companies, which hate upgrading. So they *couldn't* pivot to the 386. The customers they had just sold those bazillion ATs to would have burned their headquarters down. They were lashed to the mast of the 286.
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Jason Lefkowitzreplied to Jason Lefkowitz last edited by
@loke @maddiefuzz This had knock-on effects too. IBM and Microsoft were working at the time on what they both planned to be the replacement for DOS, called OS/2. OS/2 was meant to be multitasking from the ground up.
But IBM had all those corporate customers they'd sold all those ATs, so they insisted OS/2 had to work on the 286. Which was tough, because of the 286's multitasking limitations.
Microsoft wanted to just write for the 386, but IBM wouldn't go for it. So eventually Microsoft split off and built their own product, which they called "Windows."
Which of course went on to own the world, while OS/2 became a footnote.