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4
Theory of Operation
4.1
Introduction
This section describes the notebook theory of operation.
4.2
Notebook Functional Description
Functionally, the notebook computer consists of the following major
subsystems:
•
Processor and Memory Subsystem
•
I/O Subsystem
•
Video Subsystem
•
Hard Disk Subsystem
•
Floppy Disk Subsystem
•
PCMCIA Subsystem
•
Power Subsystem
A functional block diagram of the Extensa Notebook is shown in Figure 4-1.
4.2.1
Processor/Memory Subsystems
The Processor function, housed on the Main Board, is implemented with a
100 MHz Intel Pentium Processor. The processor operates in conjunction
with RAM and ROM Memory on the Memory Board and other control logic
on the Main Board to process software instructions (BIOS, Windows 95, and
Applications).
The memory subsystem, implemented on the Main Board and optional Dual
Inline Memory Modules, provides 8 MB (expandable to 40 MB) of fast DRAM
memory, 128 bytes of CMOS RAM (battery backed up) and 256 KB of Flash
ROM for system and video BIOS storage. Tables 4-1 through 4-3 contain the
Notebook I/O address map, DMA channel assignments and IRQ interrupt
level assignments respectively.
Theory of Operation
4-1