UMB
Upper Memory Block
                                                 
Traditionally, memory between 640K and 1 MB has
been "reserved" for special purposes such as
video memory and ROM.

On 386+ computers, it is possible to map extended
memory into the unused areas of reserved memory.

The resulting islands of memory are called
Upper Memory Blocks, or UMBs.
                                                 
  DOS fn 5803H (along with fn 48H) provide
access to UMBs.  See UMB in the Index.
  DEVICE=HIMEM.SYS      use in CONFIG.SYS
DEVICE=EMM386.EXE     to enable access
DOS=UMB               to UMBs
  DEVICEHIGH= load device drivers into UMBs

qMemUMB