Specifications

4 - 4
4.2.3 System Memory Map
The 80286 used as the central processing unit (CPU) on the Little Board/286 has a memory
address space which is defined by 24 address bits. Therefore, it can address 16 megabytes of
memory. The board's memory space is utilized as indicated in Table 4-1.
Basically, the board's onboard resources (including up to 4 MB DRAM, optional video module,
byte-wide sockets, and ROM-BIOS) occupy the first megabyte (starting at 00000h), and also
provide an option of onboard extended memory (384K or more) starting at 100000h. The
remainder of the board's 16 megabyte memory space is available for expansion cards on the
board's 16-bit AT Expansion Bus.
Table 4-1. Little Board/286 Memory Map
Memory Function
FE0000-FFFFFFh Duplicates onboard memory at 0e0000-0FFFFFh
100000-FDFFFFh “Extended memory” space. 384K or more can be
supplied by onboard DRAM, if 1MB or more of DRAM
is installed onboard, and jumpers are set to enable
onboard extended memory.
0F0000-0FFFFFh ROM-BIOS sockets at U10 and U11.
U10 contains “odd” address byte, and U11 contains
“even” address byte. Contains a startup vector at
address 0FFFFoh.
0E0000-0EFFFFh Duplicates onboard memory at 0F0000-0FFFFFh.
Reserved for future expansion.
0D8000-0DFFFFh Byte-wide memory socket at U33.
0C0000-0C7FFFh Byte-wide memory socket at U32.
0C0000-0CFFFFh Reserved for expansion bus ROM’s.
0A0000-0BFFFFh Normally contains video RAM, as follows:
CGA Video: B8000 – BFFFFh
Monochrome: B0000 – B7FFFh
EGA Video: A0000 - AFFFFh
080000-09FFFFh 128k bytes onboard DRAM (optional).
000000-07FFFFh 512k bytes onboard DRAM.