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Retrocomputing

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    @tofro For example the mouse is a very good example. You had different interfaces, you had bus mice, serial mice, PS/2 mice, and USB legacy support in BIOS to support USB mice as legacy PS/2 mice. Each interface was different (bus mice could exist in different IO area and show movement differently, serial mice could be connected to different COM ports at different base addresses and interrupts and you had different serial protocols like Microsoft and MouseSystems that need the bytes interpreted differently). PS/2 had scroll wheels too. You only had a DOS driver program with your mouse. Commented Feb 12, 2024 at 9:40
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    @tofro How do you get DOS programs to support mouse? By providing a DOS program as the mouse driver for the specific mouse, and DOS programs can use a common driver API and does not need to know what kind of mouse there is on what kind of bus. It would be unlikely that a game would add support for different mice. Or different CD-ROM drives. Commented Feb 12, 2024 at 10:03
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    @tofro My point exactly! The mouse driver is also a file on DOS disk, and needs DOS to be able to load it. If you were making a game that can run without being loaded from DOS, you have no mouse driver and your game would need to support each and every mouse interface and protocol by itself. And also difficult to run the game from a file on disk, if there is no DOS, or even if started from DOS, you can't access files if you throw away the layer of DOS which provides you a file system. If you had a single hardware, like gaming console, you could run anything on bare metal without DOS/BIOS. Commented Feb 12, 2024 at 10:30
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    Int 33h is a standardised DOS mouse interface. Whether it is "part of DOS" or not, or "part of BIOS", is semantics, but most DOS applications would use int 33h to talk to hardware-specific drivers, not implement the mouse drivers themselves. Sound and video are better examples of things largely done by direct hardware access. Commented Feb 12, 2024 at 11:12
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    @winny You could do anything you wanted and nothing would stop you. Except for things like disk caches which might have pending writes, so shutting down DOS and throwing it out was not an expected or supported operation. And in 386 days, you could boot into DOS and load Linux kernel and start it so it was actually done too. Booter games were also converted to COM files and they did not expect DOS present. Commented Feb 12, 2024 at 12:58