Acer Extensa 450 Maintenance Manual

4
Theory of Operation
4.1Introduction
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...

Figure 4-1   Notebook Functional Block Diagram
   
4-2  Theory 

 
Table 4-1   Extensa Series I/O Address Map
Address Range Device
000-00F DMA Controller 1 
020-021 Interrupt Controller -1
022-023 M1429 Registers
040-043 T imer 1
060-06E Keyboard Controller 8742 Chip Select
070-071 Real Time Clock and NMI Mask
080-08F DMA Page Register
0A0-0A1 Interrupt Controller 2
0C0-0DF DMA Controller -2
1F0-1F7 Hard Disk Select
178,,17A 6377 Registers
1F0-1F7 Hard Disk Select
3F6,,3F7, 
278-27F Parallel Port 3
35F, 36F Special I/O Ports
378,,37A Parallel Port 2
3BC-3BE Parallel...

Table 4-2  DMA Channels
Controller Channel Address Function
1 0 0087 Spare
1 1 0083 Spare
1 2 0081 Diskette
1 3 0082 Spare
2 4 Cascade Cascade
2 5 008B Spare
2 6 0089 Spare
2 7 008A Spare
Table 4-3  IRQ Interrupt Levels
Priority Interrupt
NumberInterrupt Source
1 SMI Power management unit
2  NMI Parity Error Detected,,I/O Channel Error
3 IRQ0 Interval Timer,,Counter 0 Output
4 IRQ1 Keyboard
IRQ 2 Interrupt from controller 2 (cascade)
5 IRQ8 Real Time Clock
6 IRQ 9 Cascaded to INT 0AH (IRQ 2)
7 IRQ10...

nNote:  A PCMCIA card can use IRQ 3, 4, 5, 7, 9 and 11 as long as it does not
conflict with the interrupt address of any other device.
4.2.2   I/O Subsystem
The I/O subsystem, implemented with an NS87334 VJG Super I/O Controller Chip,
provides for such functions as internal Hard Drive control, floppy drive control,
serial and parallel ports and support for the Serial Infrared port. The Super I/O
Controller includes the following features: .
·100 percent compatible with ISA, EISA, and Micro-channel...

·Includes protection circuit against damage caused when printer is
powered up, or operated at higher voltages
· Integral IDE controller
·Provides a complete IDE interface with DMA control (except for
optional buffers)
·Integral address decoder- provides selection of all primary and secondary ISA
addresses including COM1-4 and LPT1-3.
·Enhanced Power Management Function
·Special configuration registers for power down
·Enhanced programmable power -down and wake-up modes
·Auto power -down and wake-up modes...

4.2.3.1   External VGA Drive Capability
On the Extensa 450, the external VGA port is provided by the port adaptor fixture
in the form of a 15-pin, female, D-type connector which can be used to drive an
external CR T (standard VGA modes with resolutions of 800 X 600 X 256, or 640 X
480 X 256 ).
4.2.4   Hard Disk Subsystem
The Hard Disk Subsystem, controlled by the IDE interface compatible NS87334
VJG Super I/O Controller on  the Main Board, provides disk storage for all system
software and user files....

· Direct connection to ISA (PC AT) Bus
· Direct connection to PCMCIA 2.0 Bus
· PCMCIA 2.0- and JEIDA 4.1-compliant
· 82365SL-compatible register set, ExCA-compatible
· Automatic Low-power Dynamic Mode for lowest power consumption
· Programmable Suspend Mode
· Five programmable memory windows per socket
· Two I/O windows per socket
· Programmable card access cycle timing
· 8- or 16-bit CPU interface
· 8- or 16-bit PCMCIA interface support
· ATA disk interface support
· Automatic flash memory timing...

· LCD standby mode
·Hard disk standby mode
·System standby/suspend mode
·Battery-low warning
·Standby/suspend upon battery low
4.2.7.2   AC Adapter
The notebook uses an AC adapter with built in over voltage and short circuit
protection.
The adapter can with stand a continuous short-circuit to DC output without
damage to the notebook logic components. The adapter operates in shut down mode
shorting Vo trail and resets to the normal power mode after the fault condition is
removed. 
4.2.7.3   Primary...

4.2.7.4   Secondary Battery Pack
As an optional feature, the Floppy Drive can be removed from the notebook and a
Li-Ion (Lithium Ion) secondary battery pack can be installed in the same cavity to
provide additional battery operating time.
   
4-10  Theory