48H (BX=ffffH) determine largest available block
48H allocate a block of memory
49H free an allocated block of memory
4aH resize (shrink/expand) a memory block
3306H See if DOS is in the HMA INT 2fH 4axxH Suballocate in the HMA
XMS Services XMS memory/HMA control EMM Services LIM-EMS memory
DPMI Services DOS Protected Mode Interface services
Accessing Upper Memory how to allocate a UMB
Program Startup & Exit memory considerations when a program starts
CONFIG.SYS Commands (DOS=, DEVICEHIGH=, etc. affect memory)
INT 12H total conventional memory INT 15H 88H total extended memory