|
high memory
|
|||
|
segment
|
offset
|
size
|
contents
|
|
0000h
|
0000h
|
1024
|
interrupt
vector table
|
|
|
0400h
|
172
|
BIOS
communication area
|
|
|
04ACh
|
68
|
reserved
by IBM
|
|
|
04F0h
|
16
|
user
communication area
|
|
|
0500h
|
256
|
DOS
communication area
|
|
|
0600h
|
varies
|
operating 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 |
|
9000h
|
FFFFh
|
|
highest
address of user memory
|
|
A000h
|
0000h
|
128K
|
reserved
area of ROM
|
|
A000h
|
0000h
|
|
beginning
of area used by EGA and PS/2 video systems
|
|
B000h
|
0000h
|
4000
|
monochrome
video memory
|
|
|
0800h
|
16K
|
color
graphics adaptor (CGA) video memory
|
|
C000h
|
0000h
|
192K
|
ROM
expansion and control area
|
|
|
8000h
|
|
ROM
for hard disk
|
|
D000h
|
|
|
ROM
expansion and control area
|
|
E000h
|
|
|
ROM
expansion and control area
|
|
F000h
|
0000h
|
16K
|
reserved
ROM
|
|
|
4000h
|
40K
|
base
system ROM, ROM BASIC
|
|
|
E000h
|
8K
|
ROM
BIOS
|
|
low memory
| |||