Comment by JdeBP
6 hours ago
Yes, outwith the idea of Family API programs (which couldn't use Presentation Manager and whatnot anyway) OS/2 1.x did target the 286 as a minimum. But that doesn't mean that DOS+Windows didn't use the features.
It did. It was bi-modal. There were at one point switches to the WIN command to tell it whether to come up in real mode or 286 protected mode. In the latter it definitely did use the features of protected mode.
It was the bi-modal nature that was the problem. Essentially, they had to design a whole layer that simulated when in real mode all of the load-on-demand stuff that the processor architecture supplied for free in 286 protected mode, and make it so that the thing would all work either way with no changes to applications.
> There were at one point switches to the WIN command to tell it whether to come up in real mode or 286 protected mode. In the latter it definitely did use the features of protected mode.
Windows 3.0’s WIN.COM supported:
/R for real mode (8086)
/S for standard mode (16-bit protected mode)
/E for 386 Enhanced Mode (32-bit virtual machine manager (VMM), running Windows in VM1, and DOS apps in VM2+)