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include ebios.inc
 
VxDcall EBIOS_Get_Unused_Mem
 
The EBIOS_Get_Unused_Mem service returns information about any unused
portion of the EBIOS region.
 
This service is intended for the use of the virtual MS-DOS manager.
 
This service has no parameters.
 
Return Value
 
The carry flag is clear if the service is successful. The EAX register
contains the segment address of start of unused EBIOS region, and the ECX
register contains the size of the region in paragraphs. This size is zero if
there is no unused EBIOS region. If the zero flag is set, the unused EBIOS
region is global, that is, the region is in the same physical page in all
virtual machines. Otherwise, the unused EBIOS region is local and is in
different physical pages in each virtual machine.
 
The carry flag is set if the EBIOS device is not installed or all EBIOS
memory is used by EBIOS.
 
Comments
 
On some machines, the size of the EBIOS region is not an even multiple of
pages. Since the system requires that the EBIOS region be rounded to page
boundaries, part of the EBIOS region may be unused.
 
If the EBIOS region is below the first V86 page, this service must set the
carry flag and return.
 
Uses
 
EAX, ECX, Flags
 
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