Upon return from XMS Functions, the AX register indicates success or
When a function fails, the BL register will contain an error code. All
XMS error codes have bit 7 set; so BL will be >= 80H.
80H Function not implemented
81H A VDISK device is detected (screws up allocations...)
82H An A20 error occurred
8eH General XMM driver error
8fH Unrecoverable XMM driver error
91H HMA is already in use
92H DX is less than /HMAMIN= parm
94H A20 line is still enabled
a0H All extended memory is allocated
a1H All XMS handles are in use
a8H Invalid overlap in move
acH Lock count has overflowed
b0H A smaller UMB is available
b1H No UMBs are available
b2H UMB segment number is invalid
90H Attribute type undefined