On 12/26/21 3:18 PM, Aitor Santamaría wrote:
My point here is, NT has indeed quite a bunch of more stable and better thought features of an operating system that was conceived in the late 80's rather in the late 70's (a better filesystem, more suitable to networks, and basically, a brand new Win32 API more suitable for writing stable applications), but I don't see multitasking as the feature that killed DOS.
It was the feature that killed DOS. It's not that DOS couldn't multitask (though that depends a bit on how you define multitasking), it's that it couldn't do so safely and fully back-compatibly. The first generation x86 processors that DOS originally ran on didn't have any features to allow the operating system to isolate applications from the hardware. So tons of applications opted to interact with the hardware directly, because that was often more performant. By the time that the 286 and 386 added features that allowed robust multitasking, there were too many applications that interacted directly with the hardware, and by the time that features that would allow the OS to emulate hardware showed up in the 386, there were just too many different bits of hardware that the OS might need to emulate. So at that point, any DOS that wanted to multitask had to choose whether to maintain back-compatibility with applications that performed direct hardware access, at the cost of less completely isolating applications from each other, and from the OS, or whether to go for strict isolation, at the cost of back compatibility.
Jon Brase
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