Section 4 Theory Of Operation; Introduction; Notebook Functional Description; Processor/Memory Subsystems - Texas Instruments Extensa 450 Series Maintenance Manual

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
Serial Infrared 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 75mhz
IntelDX4 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).
Primary control for the Processor/Memory subsystem is implemented with the
M1429L PC/AT Chipset. Address buffering and real time clock function is
implemented with an M1441L.
The memory subsystem, implemented on the Memory Board and optional Dual
Inline Memory Modules, provides 4MB (expandable to 32 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
Theory 4-1