Memory Map - NEC SX Service And Reference Manual

Memory Map

The system supports system and video shadowing, both controlled through
complementary metal oxide semiconductor (CMOS). The system supports BIOS
as a cacheable area with write protection. The following table shows 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
0F0000h-0FFFFFh
100000h-1FFFFFFh
200000h-FFFFFFFh
9-12 Specifications
System Memory Map
Size Function
768 bytes BIOS Interrupt Vector Table
256 bytes BIOS Stack Area
256 bytes BIOS Data Area
639 KB Applications Memory (used by the OS, 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
256 MB Extended Memory