Acer Extensa 900 Maintenance Manual

                                                                                                            Theory of Operation  4-15  
functions. All popular 5.25-inch and 3.5-inch floppy disk drives, including the 2.88 MB, 
3.5-inch floppy disk drive, are supported. In addition, automatic media sense and 
2 Mbps tape drive support are provided by the FDC.
The two UAR Ts are fully NS16450 and NS16550 compatible. Both ports support MIDI 
baud rates and one port also supports IrDA 1.0 SIR (with data rate...

4-16   Theory of Operation
¨Extended Capabilities Port (ECP) compatible, including level 2 support
¨Bidirectional under either software or hardware control
¨Compatible with ISA, and EISA, architectures
¨Ability to multiplex FDC signals on parallel port pins allows use of an external 
Floppy Disk Drive (FDD)
¨Includes protection circuit to prevent damage to the parallel port when a 
connected printer is powered up or is operated at a higher voltage
¨UARTs
¨Software compatible with the PC16550A and...

                                                                                                            Theory of Operation  4-17  
¨16 bit addressing (full programmable)
¨10 selectable IRQs
¨4 selectable DMA Channels
¨3 SIRQ Inputs allows external devices to mapping IRQs
¨100-pin TQFP package - PC87338VJG
4.2.8 Hard Disk Drive Subsystem
The Hard Disk Drive Subsystem, implemented on the Main Board Board and on the 
associated hard disk drive module(s), provides disk storage for all system software...

4-18   Theory of Operation
¨CMDs complete set of 32-bit drivers handle both DMA and PIO
¨Fully compatible with the latest PCI, PCI IDE, ATA-2, Enhanced IDE, Fast IDE, 
ATAPI, plug and play, and ATA-2 Power Management Feature Set
¨Fully supports all ATAPI-compatible devices, including CD-ROM, tape, MO, and 
other devices
¨Fully supports legacy (IRQ 14 and 15)
¨Hardware and software mode switching and chip enable/disable capabilities
¨Programmable read-ahead and write-back buffers enhance transfer rates...

                                                                                                            Theory of Operation  4-19  
8-, 16-, and 32-bit cards using full 32-bit PCI cycles for maximum performance. 
Independent 32-bit write buffers allow fast-posted writes to improve system-bus 
utilization.
An advanced CMOS process is used to achieve low system-power consumption while 
operating at PCI clock rates up to 33 MHz. Several low-power modes allow the host 
power -management system to further...

4-20   Theory of Operation
¨Supports PC/PCI DMA on both PC Card sockets
¨Supports Zoom Video Mode
¨Supports Ring Indicate
¨Packaged in 208-pin Thin Plastic Quad Flatpack (PDV)
4.2.11   Power Subsystem
The notebook is equipped with a software/hardware monitored/controlled Power 
Subsystem that minimizes battery usage for prolonged battery operation and 
automatically recharges the batteries when the notebook is used with an AC adapter.
The control for the power subsystem is implemented with the ALI M6377...

                                                                                                            Theory of Operation  4-21  
Figure 4-3  Power Subsystem Simplified Block Diagram
UMA
DC/DC CONVERTER
DCBATOUT
CHARGER
8MB
DRAM/
DIMM*1
M+5V
M+3.3V
HDD/
CD
FDD
PCI1130SW
SWM1521
M1523
9088MAL
CPU
+3.3V
SW M+5V
SW
+2.9VM+2.9V
SW M+7V
AUDIO_VDDES1878S
SW
FLASH
ROM
+12V M+12V
+3.3V
+5V
+3.3V
+5V
+5V VGA_VDD M+5V
M+3.3V
M+5V
M+5V
L2 CACHE
HDD
PCI064387338
+5V
M6375
M38813
65550/S3VRAMRESUME
GLUE
LOGIC...

4-22   Theory of Operation
4.2.11.1 ALI M6377 Power Management Unit
The major features of the ALI M6377 Power Management Unit include:
¨Three operation states
— ON state
— DOZE state
— SLEEP state
¨Programmable DOZE and SLEEP timers
¨Programmable EL timer for backlight control
¨Three output pins depending on operation state, each pin is programmable and 
power configurable.
¨Provide system activity monitoring, including:
¨Video
¨Hard disk drive
¨Floppy disk drive
¨Serial port
¨Keyboard
¨Parallel port...

                                                                                                            Theory of Operation  4-23  
         Table 4-5  M6377 GPIO Port Definitions
ItemDescription
GPIO17
(W/R)1:  Connect serial BUS with charger ROM.
0:  Disconnect serial BUS with charger ROM.
GPIO20 is the CLK and GPIO21 is the DATA for the serial BUS.
GPIO16Reserved
GPIO15
(W/R)1:  CPU high temperature SMI is allowed.
0:  CPU low temperature SMI is allowed.
GPIO14
(W/R)1:  Connect the ZV BUS with...

4-24   Theory of Operation
Table 4-5  M6377 GPIO Port Definitions (Continued)
ItemDescription
GPIO20
(W/R)GPIO20 is the common CLK for below serial BUS:
A.  For Charger ROM, Inverter ROM, MPB ROM serial BUS.
B.  For Brightness & Contrast control.
C.  For Feature board.
GPIO37
(W/R)GPIO37 is serial DATA for Feature board serial BUS, and GPIO20 is the serial CLK.
GPIO36
(W/R)1:  Normally
0:  Disable MPB power.
GPIO35
GPIO34
GPIO33
(W/R)The system use 3-wire BUS to communicate with thermal sensor (DS1620)....