- Early versions of Windows ran on top of MS-DOS and had limitations like lack of security and multitasking. Microsoft developed Windows NT to address these issues by building it as a standalone operating system without reliance on MS-DOS. - Windows NT was designed with goals of extensibility, portability, reliability, compatibility, and performance. It uses features like a modular design, object model, and virtual memory to fulfill these goals. - Memory management in Windows involves virtual memory and paging of memory contents between physical memory and disk by the Virtual Memory Manager. Processor management is based on preemptive multitasking of threads.