PC-DOS and MS-DOS memory map

high memory
0000h0000h1024interrupt vector table
 0400h172BIOS communication area
 04ACh68reserved by IBM
 04F0h16user communication area
 0500h256DOS communication area
 0600hvariesoperating system:
IBMBIO.COM (DOS interface to the BIOS)
IBMDOS.COM (DOS interrupt handlers and interrupt 21h service routines
DOS buffers, control areas, and device drivers
COMMAND.COM (resident portion), interrupt 22h, 23h, and 24h handlers, routine to reload transient portion of COMMAND.COM
memory-resident utilities
transient applications
transient portion of COMMAND.COM
9000hFFFFh highest address of user memory
A000h0000h128Kreserved area of ROM
A000h0000h beginning of area used by EGA and PS/2 video systems
B000h0000h4000monochrome video memory
 0800h16Kcolor graphics adaptor (CGA) video memory
C000h0000h192KROM expansion and control area
 8000h ROM for hard disk
D000h  ROM expansion and control area
E000h  ROM expansion and control area
F000h0000h16Kreserved ROM
 4000h40Kbase system ROM, ROM BASIC
low memory