INT 31H 0504H: Allocate Linear Memory Block

                                                    Compatibility: DPMI 1.0+ 
 Expects: AX    0504H
          EBX   desired linear address or 0
          ECX   size of block, in bytes (must not be 0)
          EDX   flags:  bit 0: 1=create committed pages
                               0=create uncommitted pages
                         1-31: (reserved; should be 0)
 Returns: CF    NC (clear) if successful; else AX = DPMI Error Code
          EBX   linear address of allocated block
          ESI   handle used to resize and free this block
    Info: Allocates a block of page-aligned linear address space.  The base
          address of the block may be specified by the client and the
          allocated pages may be committed or uncommitted.

          If EBX is 0 on entry, then the host can pick any available linear

See Also: DPMI API
          INT 2fH: Multiplex Interrupt
          DOS Functions