上位內存塊
upper memory block(UMB) Up to 64 {kilobytes} of the {expanded memory page frame} above the first 64 kilobytes. The UMB can be used to store {TSR} programs or {device drivers} thereby freeing parts of the precious {conventional memory}. The UMB is provided by special memory manager programs; many {EMM}s can provide UMB as well. (1996-01-10)