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

5800H query allocation strategy       5801H set allocation strategy

5802H query upper-memory link         5803H set upper-memory link

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)

MCB Memory Control Block layout    PSP fields wNextSeg, et al. are relevant

INT 12H total conventional memory  INT 15H 88H total extended memory

TSR/Popup Functions                         Service Groups   DOS Functions