VOGONS


First post, by superfury

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Does Windows 3.x simulate V86 mode using real mode with LOADALL on a 80286 CPU?

Then it for example can set SS to use a DPL of 3 to make it run in user mode? Or is that simply not possible?
How does it make sure to catch thinks like port accesses in real mode(for it's Windows device drivers, for example the HDD)?

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Reply 2 of 7, by superfury

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But can Windows virtualize anything in real mode? Like virtual ports or port access detection(virtualizing hardware), like Windows 95 can in V86 mode? Is that even possible?

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Reply 4 of 7, by superfury

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Won't that cause disk corruption issues when switching between MS-DOS and Windows(using Akt-Tab)? If a disk write/read gets broken up and Windows(because it gets control) is switched in and changes things on the hard disk, the MS-DOS app won't know and the both of them might corrupt when reading/writing files?

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Reply 6 of 7, by jakethompson1

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superfury wrote on 2020-05-21, 22:06:

Won't that cause disk corruption issues when switching between MS-DOS and Windows(using Akt-Tab)? If a disk write/read gets broken up and Windows(because it gets control) is switched in and changes things on the hard disk, the MS-DOS app won't know and the both of them might corrupt when reading/writing files?

I don't have a complete technical answer other than that for this specific issue, Windows and DOS applications go through DOS for disk access, so I think any of this i/o would be properly serialized. This is why 32-bit disk access was such a big deal. I think you might enjoy reading about the Task Switcher in this magazine article though. https://books.google.com/books?id=Xb5VnujctzA … epage&q&f=false