CME37786HX
RTD Embedded Technologies, Inc.
70
Memory Map
The ISA portion of the cpuModule addresses memory using 24 address lines. This allows a maxi-
mum of 2
24
locations, or 16 Megabytes of memory.
The table below shows how memory in the first megabyte is allocated in the system.
Memory beyond the first megabyte can be accessed in real mode, by using EMS or a similar memory
manager. See your OS or programming language references for information on memory managers.
Table 36: First Megabyte Memory Map
F0000-FFFFFh
BIOS ROM
256 KB BIOS in Flash EPROM, shadowed into DRAM dur-
ing runtime.
E0000-EFFFFh
BIOS Decompres-
sion
Used during boot to decompress the BIOS. This should not be
used for hardware devices, however, it is free for use after the
system has booted.
D0000-FFFFh
Available
This area is always available for hardware devices
CC000-CFFFFh
(typical)
Legacy USB
This area is used for USB keyboard and USB boot. It can be
freed by disabling USB Keyboard, and by not attaching any
USB storage devices. Alternately, the USB controller can be
disabled.
This area is always immediately after the video BIOS.
C0000-CBFFFh
(typical)
Video BIOS
If an external video card is used, the size of this area may
change.
B8000-BFFFFh CGA Memory
Used for CGA video modes
B0000-B7FFFh Mono Memory
Used for Monochrome video modes
A0000-AFFFFh EGA/VGA Memory Used for EGA/VGA video modes
9FFFFh-00502h
DOS reserved memory area
00501h-00400h
BIOS data area
003FFh-00000h
Interrupt vector area
Содержание cpuModule CME37786HX
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