Memory Map; System Video - NEC VERSA 6220 Service Manual

1-16 Technical Information

Memory Map

The system supports system and video memory shadowing, both controlled through com-
plementary metal oxide semiconductor (CMOS settings). The system supports BIOS as a
cacheable area with write protection. Table 1-2 lists the system's memory map.
Memory Space
000000-0002FFh
000300-0003FFh
000400-0004FFh
000500-09FFFFh
0A0000-0AFFFFh
0B0000-0B7FFFh
0B8000-0BFFFFh
0C0000-0CBFFFh
0CC000-0CFFFFh
0D0000-0DFFFFh
0E0000-0EFFFFh
0F0000-0FFFFFh
100000-1FFFFFFh
2000000-5FFFFFFh

SYSTEM VIDEO

The system's LCD operates using the NeoMagic NMG4 VGA Controller. Video signals
travel from the controller through the system's 15-pin D-SUB connector using 5 volts.
System video integrates a PCI-bus interface. The system ships with 2 MB Video RAM
(VRAM). It supports video modes up to 1024 x 768 with 64K colors in LCD mode.
See Appendix B for a list of Video modes.
Table 1-2 Memory Map
Size Function
768 bytes BIOS Interrupt Vector Table
256 bytes BIOS Stack Area
256 bytes BIOS Data Area
639 KB Application Memory (used by the Operating
System, device drivers, TSRs, and all DOS
applications)
64 KB Video Buffer (EGA and VGA)
32 KB Video buffer (monochrome, CGA color, VGA
monochrome)
32 KB Video Buffer (CGA, EGA color, and VGA color)
48 KB Video ROM (EGA and VGA)
16 KB Unused, (Reserved for Adapter ROMs and other
devices requiring ROMs)
64 KB Used by Adapter ROMs (i.e., network controllers,
hard disk controllers, SCSI host adapters)
64 KB Used by System ROM adapters (i.e., network
controllers with boot capability)
64 KB System AMIBIOS (includes Setup and hard disk
drive utilities)
32 MB Built-in Extended Memory
64 MB Extended Memory