Difference between MS-DOS and Window XP Memory Management?

DOS Memory Management: Under MS-DOS, device driver and TSR modules can take up large amounts of conventional memory. A memory manager can move some of these into upper memory blocks or the High Memory Area, freeing up conventional&memory and creating a larger TPA. Memory managers also control access to extended memory, allowing it to be accessed via XMS, or as expanded memory via EMS. Popular DOS memory mangers include EMM386 and QEMM.

Windows Memory Management: Memory management in Microsoft Windows operating systems has evolved into a rich and sophisticated architecture, capable of scaling from the tiny embedded platforms (where Windows executes from ROM) all the way up to the multi-terabyte NUMA configurations, taking full advantage of all capabilities of existing and future hardware designs. With each release of Windows, memory management supports many new features and capabilities. Advances in algorithms and techniques yield a rich and sophisticated code base, which is maintained as a single code base for all platforms and SKUs. Memory management improvements in Windows Vista focused on areas such as dynamic system address space, enhanced NUMA and large system/page support, advanced video model support, I/O and section access, and robustness and diagnosability.