Physical memory map:

00000000-00000400: Real mode IDT
00000400-00000500: Bios data area
00000500-000xxxxx: DOS
000xxxxx-000yyyyy: Relocateable OS code
000yyyyy-000wwwww: Relocateable OS data
000wwwww-0009a000: Allocateable base memory ( For system stacks)
0009a000-000a0000: System page directory and tables (enough to map 16Mb 
			+ Base memory)
000a0000-000c0000: VIDEO MEMORY
000c0000-000effff: Misc EPROMS 
000f0000-000fffff: BIOS EPROMS
00100000-00200000: Unmapped if A20 line not set or mapped if so
00200000-00210000: File buffers and FCBs (start of extended memory)
00210000-xxxxxxxx: Allocatable extended memory

Linear memory map of each non-system process:
00000000-00000fff: Unmapped, reserved to trap null pointers
00001000-003bbfff: Code / static DATA
003bf000-003c0000: System stack (unexpandable)
003c0000-003fffff: User stack (4K Allocated, auto-expand down to a 256K limit)
00400000-00800000: Memory allocated at run-time (dynamic data)
FFFC0000-FFFFFFFF: TSS maps, start at top and work downward.  TSSs are remapped
			here so that tasks can get at their TSS memory without
			switching to the system memory map.

System Linear memory map: ( Data segment)
Starts with yyyyy mapped at address 0 and extends throughout physical 
memory

Predefined selectors (GDT):
0b:	System call gate
10/13:	Absolute data segment, same as physical memory if system is mapped
18:	System code segment.  NOT the same as system data segment
20:	System data segment.
28:	16 Bit code segment, for mode switches
30:	16 Bit data segment, for mode switches

Predefined selectors (LDT):
07:	User Code
0f:	User data
17:	User stack
1c:	User stack for ring 0 switch (system stack for process)