Int 21 Fn 2520  P - Phar Lap 386/dos-extender Vmm - Get Memory Statistics  [E]

   AX = 2520h
   DS:EDX -> pointer to buffer at least 100 bytes in size (see below)
   BL = 0 (don't reset VM stats), 1 (reset VM stats)

Return: carry flag clear

Format of VM stats buffer:
Offset Size    Description
 00h   DWORD   VM status
       0001h VM subsystem is present
       0000h VM not present
 04h   DWORD   "nconvpg" number of conventional memory pages available
 08h   DWORD   "nbimpg" number of Compaq built-in memory pages available
 0Ch   DWORD   "nextpg" total number of extended memory pages
 10h   DWORD   "extlim" extender memory pages limit
 14h   DWORD   "aphyspg" number of physical memory pages allocated to appl
 18h   DWORD   "alockpg" number of locked pages owned by application
 1Ch   DWORD   "sysphyspg" number physical memory pages allocated to system
 20h   DWORD   "nfreepg" number of free physical pages; approx if EMS VCPI
 24h   DWORD   linear address of beginning of application address space
 28h   DWORD   linear address of end of application address space
 2Ch   DWORD   number of seconds since last time VM stats were reset
 30h   DWORD   number of page faults since last time
 34h   DWORD   number of pages written to swap file since last time
 38h   DWORD   number of reclaimed pages (page faults on swapped pages)
 3Ch   DWORD   number of virtual pages allocated to the application
 40h   DWORD   size in pages of swap file
 44h   DWORD   number of system pages allocated with EMS calls
 48h   DWORD   minimum number of conventional memory pages
 4Ch   DWORD   maximum size in pages to which swap file can be increased
 50h   DWORD   "vmflags"
       bit 0 = 1 if page fault in progress
---v4.0+ ---
 54h   DWORD   number of physical pages guaranteed to be free
 58h   DWORD   number of free physical pages currently available
 5Ch   DWORD   size in pages of largest free block of memory (including disk
         swap space)
 60h   DWORD   reserved