INT 4B - Virtual DMA SpecificationA set of interrupt calls which permit the use of DMA even on systems running in protected or Virtual-86 mode with their address remapping, or systems such as Micro Channel PSIBM PS/2, any model/2s with multiple bus masters independently performing DMA operations. (VDSsee Virtual DMA Specification) - GET VERSION
	AX = 8102h
	DX = 0000h
Return: CF clear if successful
	    AH = major version number
	    AL = minor version number
	    BX = product number (see #03217)
	    CX = product revision number
		always 0000h for QMAPS and HPMM.SYS
		always 0001h for Microsoft's EMM386.EXE v4.20-4.41
	    DX = flags (see #03219)
	    SI:DI = maximum DMAsee Direct Memory Access buffer size
	CF set on error
	    AL = error code (see #03218)
Note:	bit 5 of 0040h:007Bh is supposed to be set if VDSsee Virtual DMA Specification is supported; this is
	  apparently not always the case
SeeAlso: INT 2C/AX=002Bh,INT 31/AX=0400h,MEM 0040h:007Bh"4Bh"
Index:	installation check;Virtual DMA SpecificationA set of interrupt calls which permit the use of DMA even on systems running in protected or Virtual-86 mode with their address remapping, or systems such as Micro Channel PSIBM PS/2, any model/2s with multiple bus masters independently performing DMA operations.


(Table 03217)
Values for VDSsee Virtual DMA Specification product number:
 0000h	for Quadtel's QMAPS and Hewlett-Packard's HPMM.SYS
 0001h	for Microsoft's EMM386.EXE
 0003h	for Windows 3.x WIN386.EXE
 0300h	OS/2 (all versions to date)
 0EDCh	for DR DOS 6.0 EMM386.SYS
 4560h	("E`") for Qualitas' 386MAX
 4D43h	("MC") for V Communications' Memory Commander
 5145h	("QE") for Quarterdeck's QEMM-386
 524Dh	("RM") for Helix's Netroom RM386


(Table 03218)
Values for VDSsee Virtual DMA Specification error code:
 01h	region not in contiguous memory
 02h	region crossed a physical alignment boundary
 03h	unable to lock pages
 04h	no buffer available
 05h	region too large for buffer
 06h	buffer currently in use
 07h	invalid memory region
 08h	region was not locked
 09h	number of physical pages greater than table length
 0Ah	invalid buffer ID
 0Bh	copy out of buffer range
 0Ch	invalid DMAsee Direct Memory Access channel number
 0Dh	disable count overflow
 0Eh	disable count underflow
 0Fh	function not supported
 10h	reserved flag bits set in DX


Bitfields for VDSsee Virtual DMA Specification flags:
Bit(s)	Description	(Table 03219)
 0	PCIBM PC/XTIBM PC XT bus (DMAsee Direct Memory Access in first megabyte only)
 1	physical buffer/remap region in first megabyte
 2	automatic remap enabled
 3	all memory is physically contiguous
 4-15	reserved (zero)