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Why did Windows 95 setup use three operating systems?

(devblogs.microsoft.com)
305 points mooreds | 1 comments | 17 Nov 24 19:54 UTC | HN request time: 0.318s | source
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jmclnx ◴[17 Nov 24 20:19 UTC] No.42166830[source]▶
I never thought of Windows 3.1 as an OS. The other 2 was MS-DOS and Windows 95.
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rusk ◴[17 Nov 24 21:05 UTC] No.42167247[source]▶
Agree, the terminology in those days was “shell”.

Though Windows 95 was arguably similar running atop “DOS 7” it actually imposes its own 32-bit environment with its own “protected mode” drivers once booted. Dropping to DOS reverted to “real mode”.

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tliltocatl ◴[17 Nov 24 21:13 UTC] No.42167329[source]▶
So did the lastest Win3.1 for workgroups, just MS spared all the fanfare for Win95. Not sure if the 3.1 version in the installers does.
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rusk ◴[17 Nov 24 21:15 UTC] No.42167345[source]▶
Windows 3.1 was just a graphical shell. All the drivers and stuff were still managed by DOS. You still needed to configure your system with config.sys

EDIT it’s coming back to me. Windows 3.1 did have a a subsystem for running 32 bit apps called Win32 I think that’s what you mean. This was very much in the application space though.

It still used cooperative multitasking and Win 95 introduced preemptive.

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DHowett ◴[17 Nov 24 21:54 UTC] No.42167659[source]▶
Bryan Lunduke has an article about this myth, actually!

https://lunduke.locals.com/post/4037306/myth-windows-3-1-was...

It’s backed up by another Old New Thing article at https://devblogs.microsoft.com/oldnewthing/20100517-00/?p=14...

The TL;DR is that Windows 3.1 effectively replaced DOS and acted as a hypervisor for it, while drivers could be written for Windows (and many were) or DOS (and presumably many more of those were actually distributed). The latter category was run in hypervised DOS and the results bridged to Windows callers.

(Edited after submission for accuracy and to add the Old New Thing link.)

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1. rusk ◴[18 Nov 24 00:07 UTC] No.42168490[source]▶
Thanks for that it’s very interesting. I had no idea the virtual machine system was so advanced. Device drivers and such were all still real mode but yes I can see how this would make DOS a component of Windows rather than the other way round. All for nothing if the apps aren’t bought in though!