System And Video Bios; System Memory Map - NEC POWERMATE P - SERVICE MANUAL 1996 Service And Reference Manual

1-6 Technical Information
Non-cacheable portions of memory are defined by software (see the following subsection
for a system memory map). The system does not cache the following regions:
n
video text memory block from A0000 to BFFFF
n
PCI memory space on top of main memory to 4 GB
n
any access to the PCI or AT bus
The cache can be cleared by software instructions.

System and Video BIOS

The system and video BIOS are stored in a 1 MB (128 KB by 8) flash memory device
(Flash ROM). The system BIOS uses 64 KB, the video BIOS uses 32 KB, and 32 KB is
reserved. The system BIOS is capable of being shadowed and cached through the system's
Setup utility (see Section 2 for Setup information). System BIOS is write protected and
automatically enabled.
The BIOS programs execute the Power-On Self-Test, initialize processor controllers, and
interact with the display, diskette drives, hard disks, communication devices, and
peripherals. The system BIOS also contains the Setup utility. The hardware setup default
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 removing 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.
The system memory map in shown in Table 1-2.
Memory Space
FFF80000-FFFFFFFF
04000000-07FFFFFF
01000000-03FFFFFF
00F00000-00FFFFFF
00100000-00EFFFFF
000F0000-000FFFFF
000C8000-000EFFFF
000C0000-000C7FFF
000A0000-000BFFFF
Table 1-2 System Memory Map
Size To
512 KB 4 GB
64 KB 128 MB
48 KB 64 MB
1 MB 16 MB
14 MB 15 MB
64 MB 1KB
160 KB 960 KB
32 KB 800 KB
128 KB 768 KB
Function
BIOS ROM
Second level cache (non-cacheable)
First level cache (cacheable)
Always cacheable
Optional memory space gap
Cacheable
System BIOS (shadowed in DRAM)
Expansion region (shadowed in DRAM)
Video BIOS (shadowed in DRAM
Video buffer (SMM space non-cacheable)