Theory of Operation 4-5
4.2.2 Memory Subsystem
The memory subsystem comprises the following components:
♦Main memory
♦L2 Secondary Memory (cache)
♦Flash ROM
The Extensa Series uses fast Extended Data Out (EDO) DRAM for main and video
memory and high-speed synchronous, pipelined burst SRAM for L2 cache memory.
Main BIOS and Video BIOS are stored in Flash ROM.
The Extensa 900 Series Memory Address Map is shown in Table 4-2.
Table 4-2 Memory Address Map
The DMA Channel Map is listed in Table 4-3.
Table 4-3 DMA Channel Map

4.2.2.1 Main Memory

The standard 900 Series notebook comes with 16 MB of Main memory installed on the
Main Board. Memory expansion accommodations are provided via a standard soDIMM
connector on the bottom of the Main Board Assembly. By installing a 64 MB soDIMM
module, the basic memory size can be expanded to a maximum of 80 MB.
Address Range Definition Function
000000 - 09FFFF 640 KB memory Base memory
0A0000 - 0BFFFF 128 KB video RAM Reserved for graphics display buffer
0C0000 - 0CBFFF Video BIOS Video BIOS
0E0000 - 0EFFFF
0F0000 - 0FFFFF 128 KB system BIOS System BIOS
System BIOS
100000 - FFFFFF Extended memory Onboard memory
FE0000 - FFFFFF 256 KB system ROM Duplicate of code assignment at 0E0000-0FFFFF
Controller Channel Address Function
1
1
1
1
2
2
2
2
0
1
2
3
4
5
6
7
0087
0083
0081
0082
Cascade
008B
0089
008A
Audio (option)
ECP/FIR/Audio
Diskette
ECP/FIR/Audio
Cascade
Spare
Spare
Spare