1-14 Technical Information
NEC’s Flash ROM allows fast, economical BIOS upgrades. The Flash ROM is a
reprogrammable EPROM containing both the system and video BIOS. Using the Flash
ROM to change the ROM BIOS provides the following advantages:
the BIOS upgrade is performed quickly and easily
the expense of replacing ROM BIOS chips is eliminated, so system maintenance
costs are reduced
there is less chance of inadvertently damaging the system board than when
physically replacing ROMs
new technology can be incorporated while maintaining corporate standards
network administrators can exercise company-wide control of BIOS revisions.
The BIOS programs execute the Power-On Self-Test, initialize processor controllers, and
interact with the display, diskette drives, hard disk drives, communication devices, and
peripherals. The system BIOS also contains the Setup utility. The POST copies the ROM
BIOS into RAM (shadowing) for maximum performance.
The Flash ROM allows the system and video BIOS to be upgraded with the BIOS Update
utility, without having to physically remove the ROM (see Section 2 for further information
on the BIOS Update utility). The Flash ROM supports the reprogramming of the system
BIOS and the video BIOS.
Memory Map
The system memory map is shown in Table 1-3.
Table 1-3 System Memory Map
Address Range
(Decimal)
Address Range (Hex)
Size
Description
1024 K - 1048576 K
100000 - 3FFFFFFF
1023 MB Extended memory (EDO memory)
1024 K - 524288 K
100000 - 1FFFFFFF
511 MB
Extended memory (SDRAM)
928 K - 1024 K
E8000 - FFFFF
96 KB
System BIOS
800 K - 928 K
C8000 - E7FFF
128 KB
Available high DOS memory (open
to ISA and PCI bus)
640 K - 800 K
A0000 - C7FFF
160 KB
Video memory and BIOS
639 K - 640 K
9FC00 - 9FFFF
1 KB
Extended BIOS data (movable by
memory manager software)
512 K - 639 K
80000 - 9FBFF
127 KB
Extended conventional memory
0 K - 512 K
00000 - 7FFFF
512 KB
Conventional memory