Int 4B/AX=8104h

Virtual DMA Specification - UNLOCK DMA REGION

AX = 8104h
DX = flags
bit 0:
Reserved (zero)
bit 1:
Data should be copied out of buffer
bits 2-15 reserved (zero).
ES:DI -> DMA descriptor structure (see #03221,#03222) with region size,
physical address, and buffer ID fields set

Return:
CF clear if successful
DDS physical address field set
DDS buffer ID field set (0000h if no buffer allocated)
CF set on error
AL = error code (see #03218)
DDS region size field filled wth maximum contiguous length in bytes

Note: Windows 3.0 does not check whether the region extends beyond the end of a segment

BUG: Windows 3.0 in enhanced mode does not return a correct code on error

See Also: AX=8103h - AX=8106h

Category: Disk I/O Enhancements - Int 4Bh - V

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