Int 4B Fn 8103  - Virtual Dma Specification - Lock Dma Region              [d]

   AX = 8103h
   DX = flags (see below)
   ES:DI -> DMA descriptor structure (see AX=8102h)

Return: CF clear if successful
       DDS physical address field filled in
       DDS buffer ID field filled (0000h if no buffer allocated)
   CF set on error
       AL = error code (see AX=8102h)
       DDS region size field filled wth maximum contiguous length in bytes
BUGS:  Windows 3.0 does not correctly support automatic remapping or copying
     in enhanced mode
   Windows 3.0 in enhanced mode does not return a correct code on error

See Also: AX=8104h,AX=8105h

Bitfields for flags:
 bit 0 reserved (zero)
 bit 1 data should be copied into buffer (ignored if bit 2 set)
 bit 2 buffer should not be allocated if region noncontiguous or crosses
   physical alignment boundary specified by bits 4-5
 bit 3 don't attempt automatic remap
 bit 4 region must not cross 64K physical alignment boundary
 bit 5 region must not cross 128K physical alignment boundary
 bits 6-15 reserved (zero)