Helpful Diagram

    |                                                       |   Top of Memory
    |                                                       |
    |                                                       |
    |                        /\                             |
    |                       /||\                            |
    |                        ||                             |
    |                        ||                             |
    |.......................................................|
    |                                                       |
    |                                                       |
    |             Possible Extended Memory Block            |
    |                                                       |
    |                                                       |
    |.......................................................|
    |                        ||                             |
    |                        ||                             |
    |                       \||/                            |
    |                        \/                             |
    |                                                       |
    |                                                       |
    |       Other EMBs could exist above 1088K (1MB+64K)    |
    |                                                       |
    |                                                       |
    |-------------------------------------------------------|   1088K
    |                                                       |
    |                                                       |
    |                The High Memory Area                   |
    |                                                       |
    |                                                       |
    |=======================================================|   1024K or 1MB
    |                                                       |
    |                        /\                             |
    |                       /||\                            |
    |                        ||                             |
    |                        ||                             |
    |.......................................................|
    |                                                       |
    |             Possible Upper Memory Block               |
    |.......................................................|
    |                        ||                             |
    |                        ||                             |
    |                       \||/                            |
    |                        \/                             |
    |                                                       |
    |        Other UMBs could exist between 640K and 1MB    |
    |                                                       |
    |-------------------------------------------------------|   640K
    |                                                       |
    |                                                       |
    |                                                       |
    |             Conventional or DOS Memory                |
    |                                                       |
    |                                                       |
    |                                                       |
    |                                                       |
    |                                                       |
    +-------------------------------------------------------+   0K