Ampro Corporation LITTLE BOARD P5X - Manual (Page 29)

Little Board/P5x Technical Manual
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System Memory
The module supports a single standard 64-bit DIMM position (168-pin) for the 64-bit data path to
the Pentium processor. Both EDO and SDRAM memory types are supported. Buffered DRAM is not
supported. You can install from 16M bytes to 256M bytes, depending on your memory needs.
The ROM BIOS automatically detects the size of the installed memory module and configures the
system accordingly at boot time. (No jumpering or manual configuration is required.) The amount of
memory the BIOS measured can be displayed by running Setup.
You can use EDO DRAMs or SDRAMS with access times of 60 nS or less.
Memory parity and error correction (ECC) are not supported by the chip set used on the Little
Board/P5x.
DRAM memory is allocated in the system as shown in Table 2– 7.
Table 2– 7. 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 256K byte Flash device at the factory. The top 128K bytes 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 128K bytes are mapped only to the top of
memory.
A utility program, PGM5X.COM, can be used to program the on-board Flash device. It can be used
to update the system BIOS, video BIOS, SCSI 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