Upon return from an INT 67h request to the Expanded Memory Manager, the
AH register always contains a status/error code.  If the status is not 0,
then the requested function was not performed and any values returned by
EMM are meaningless.  These errors are defined:

Status  Meaning
0    no error; function was successful; returned parms are OK

80H   internal error in EMM driver
81H   EMS memory board hardware malfunction
82H   EMM is busy
83H   invalid handle
84H   undefined function requested
85H   no more EMM handles available
86H   error in save or restore of mapping context
87H   allocation request was larger than total EMS memory
88H   allocation request was larger than available pages
89H   you can't open a handle with a page count of 0
8aH   your handle doesn't own that many pages
8bH   illegal mapping.  Only physical pages 0-3 are defined
8cH   mapping context save area is full
8dH   you can save context only once per handle
8eH   you can't restore context without a prior save
8fH   Subfunction parameter in AL not defined
                                               (EMS 4.0 codes)
90H   attribute type undefined
91H   non-volatility not supported
92H   source and dest overlap in EMS RAM (warning, not error)
93H   destination area in handle too small
94H   conventional memory overlaps EMS RAM
95H   offset too large in block move
96H   block size too large; ie, > 1M
97H   source and dest are in same handle and overlap
98H   source or dest memory type invalid (in offset 4 of packet)
9aH   alternate map register set in not supported
9bH   all alternate map/DMA register sets are all allocated
9cH   all alternate map/DMA register sets are not supported
9dH   specified alternate map/DMA register set invalid or in use
9eH   dedicated DMA channels are not supported
9fH   specified DMA channel is not supported
a0H   no handle matches specified name
a1H   the specified name already exists
a2H   source offset+region length > 1M (attempted to wrap)
a3H   contents of specified data packet are corrupted or invalid
a4H   access to this function has been denied (bad access key)

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EMM Status