ABSTRACT
Windows 3.x is non-preemption. That is, once control is passed to an application, Windows cannot regain control until the application has passed control back, by a RET. One of the touted advantages of 32-bit applications under Windows 95 is preemption. Actually, whether it be Windows 1.0 or 95, interrupt-driven device drivers, including keyboard input, must always be working in the background. When a key is pressed, a hardware interrupt is generated, which invokes the keyboard device driver. The immediate response to a key press is preemption, nothing else, and contrary to common knowledge, Windows 3.x applications can make use of similar mechanisms. Also, the DPMI host maintains preemptive time-sliced switching between VMs on Windows 3.x and 95.
