Flash Rom; System Memory Map - NEC POWERMATE 4100M Service Manual

1-6 Technical Information

Flash ROM

Machine language programs are stored in a 28F010 Flash ROM known as the system's
ROM BIOS. The system BIOS and video BIOS are contained in the ROM. The Flash ROM
is 128 KB, which consists of 64 KB of system BIOS, and 32 KB of video BIOS.
The Flash ROM allows the BIOS to be upgraded with the BIOS Update utility without re-
moving the ROM (see Section 2, Setup and Configuration). The BIOS can only be repro-
grammed by powering on the system with the BIOS Update utility diskette in Drive A.
The BIOS programs execute the Power-On Self-Test, initialize processor controllers, and
interact with the display, diskette drives, hard disks, communication devices, and peripher-
als. The system BIOS also contains the Setup program and provides VGA controller sup-
port. The hardware setup default copies the ROM BIOS into RAM (shadowing) for
maximum performance.
System BIOS is located in the upper portion of the Flash ROM and video BIOS in the
lower portion. System BIOS is located between F0000h-FFFFFh and supports shadowing
and shadowed memory. System BIOS is write protected and automatically enabled.
Video BIOS is located between C0000h and C7FFFh. If the internal video is disabled, this
range is mapped to ISA. The system memory map in shown in Table Section 1-2.
Memory Space Size
000000-07FFFF 512 KB
080000-09FFFF 128 KB
0A0000-0BFFFF 128 KB
0C0000-0C7FFF
0C8000-0EFFFF 160 KB
0F0000-0FFFFF
100000-FDFFFF 14.9 MB
FE0000-FFFFFF 128 KB
1000000- On-Board 14.9 MB
*Always non-cachable.
Table Section 1-2 System Memory Map
Function
Reserved for system base memory
Mapped to either system base memory or ISA bus*
Mapped to either on-board video memory or ISA video memory
32 KB Mapped to either on-board video BIOS or ISA video BIOS
Mapped to ISA bus
64 KB Reserved for system BIOS
Reserved for Extended and/or Expanded system memory
Mapped to ISA bus
Reserved for Extended and/or Expanded system memory