ES:DI (or ES:EDI) sel:off of 48-byte buffer to receive info
Returns: CF NC (this fn always succeeds)
ES:DI buffer contains returned info
Info: This obtains information about available physical memory, page
ES:(E)DI must point to a 48-byte buffer. On return, it contains:
+0 4 lAvailBytes largest free block, in bytes
+4 4 lUnlockedPgs pages available if left unlocked
+8 4 lLockedPgs pages available if locked
+0cH 4 lTotLinPgs linear address space size, in pages
+10H 4 lTotUnlkPgs number of unlocked pages
+14H 4 lTotFreePgs number of free pages
+18H 4 lTotPhysPgs number of physical pages
+1cH 4 lFreeLinPgs free linear address space, in pages
+20H 4 lTotSwapPgs size of page swapping file, in pages
48 size of this structure
Notes: In multi-tasking environments, these values may change at any
time, so they should be considered as "advisory."
Only the first field is guaranteed to contain meaningful data.
Other fields may contain -1 (ffffffffH) if the host doesn't