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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.
The carry flag is clear if the service is successful. The EAX register contains the segment address of the 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.
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.
EAX, ECX, Flags