Ampro Corporation LITTLE BOARD 5001451A - Manual (Page 28)

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Table 2-6. System Memory Map
Memory Address Function
FE0000h - FFFFFFh Duplicates BIOS at 0E0000-0FFFFFh.
100000h - FDFFFFh Extended memory
0E0000h - 0FFFFFh 128K ROM BIOS
0D0000h - 0DFFFFh BIOS extension option, if enabled. Otherwise, free.
0CB000h - 0CFFFFh USB
0C0000h - 0CAFFFh Video BIOS (44K)
0A0000h - 0BFFFFh Normally contains video RAM, as follows:
CGA Video: B8000-BFFFFh
Monochrome: B0000-B7FFFh
EGA and VGA video: A0000-AFFFFh
000000h - 09FFFFh Lower 640K DRAM
ROM BIOS
The standard BIOS is installed in a 256KB Flash device at the factory. The top 128KB of the Flash
device is reserved for the system BIOS, located at 000E0000h – 000FFFFFh and mirrored at the top
of the memory address space. The remaining 128KB are mapped only to the top of memory.
A utility program, PGM6X.COM, can be used to program the on-board Flash device. It can be used
to update the system BIOS, video BIOS, or user area. The utility is included on the utility diskette
that accompanies the Ampro Development Platform. The diskette includes documentation about
how to use the program.
Shadowing
To improve system performance, the contents of the ROM BIOS and video BIOS are copied into
DRAM for execution (“shadowed”), where they are accessed as 64-bit wide data. Shadowing a BIOS
ROM substantially enhances system performance. Shadowing for both the ROM and video BIOS is
built into the Ampro Extended BIOS. There is no user setting.
BIOS Recovery
If the BIOS Flash device somehow becomes corrupted, the Little Board P6d system may not boot.
In this case, the BIOS will have to be reprogrammed. A disk with an image of the current BIOS
along with the Utility PGM6X.COM may be used to restore the BIOS image. Before this can be
done, the Little Board P6d system needs to be Booted and running DOS.
Interrupt and DMA Channel Usage
The PC architecture provides several interrupt and DMA control signals. When you expand the
system through the ISA portion of the PC/104-Plus bus with MiniModule products or plug-in cards
that require either interrupt or DMA support, you must select which interrupt or DMA channel to
use. Typically this involves switches or jumpers on the expansion module. In most cases, these are
not shared resources. It is important that you configure the new module to use an interrupt or