Specifications

Theory of Operation
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For 4 Mbytes of base memory
Total
Memory
SIMM
Memory SIMM organization
4 MB None
6 MB 2 MB 1 bank 1 MB x 18-bit
8 MB 4 MB 2 banks 1 MB x 18-bit
12 MB 8 MB 1 bank 4 MB x 18-bit
20 MB 16 MB 2 bank 4 MB x 18-bit
Memory Map
The Intel386 SL supports a 25-bit physical memory address. Memory at addresses
between 0 and 20 MB (13FFFFFh) is mapped as follows:
Range Content
0000000 - 009FFFF DRAM (first 640 KB)
00A0000 - 00BFFFF mapped to EXM expansion interface; almost always
used by a video controller as video RAM
00C0000 - 00CFFFF* Write-protected DRAM containing video BIOS
00D0000 - 00EFFFF* Uncommitted; mapped to EXM expansion interface
00F0000 - 00FFFFF Write-protected DRAM containing BIOS
0100000 - 13FFFFF Extended Memory when installed or
mapped to EXM expansion interface
1400000 - 1FEFFFF Mapped to EXM expansion interface
1FF0000 - 1FFFFFF Mapped to BIOS ROM
* 0C8000 - 0EFFFF may be used either as page frame or I/O buffer (i.e. for EMM,
Ethernet, etc.) or may be used by DOS 5.0 as upper memory blocks if an EMM
driver is installed.
Note that since the EXM expansion interface has 24 address lines, some of the
"mapped to EXM expansion interface" address areas map repeatedly, or wrap-around,
in the expansion interface's address space.