Acer V12LC User manual

& K DSWHU

System Board
System Board 1-1
The V12LC is a high-performance Pentium PCI-based system board
that supports the 64-bit Pentium microprocessor running at
75/90/100/120/133/150 MHz and has a 16-KB internal write-back
cache. It utilizes the Peripheral Component Interconnect (PCI) local
bus architecture. The PCI local bus maximizes the system
performance by enabling high-speed peripherals to match the speed
of the microprocessor with its 120 MB or 132 MB per second transfer
rate in burst mode.
The system board features a slot for the PCI/ISA slot board and two
PCI enhanced IDE interfaces with a zero-wait state 11 MB per second
transfer rate and support up to four IDE devices. It has buffered serial
ports that reduce the number of interrupts to avoid slowing other
system activities. With the optional ECP/EPP function, the parallel
port transfers data at a fast 2 MB to 10 MB.
The system board has two DRAM banks composed of four 72-pin
sockets that support both single- and double-density SIMMs for a
maximum memory of 128 MB.

1-2 User’s Guide
1.1 Major Features
The system board has the following major features:
•Pentium 75/90/100/120/133/150 MHz CPU in a zero-insertion
force (ZIF) socket
•Two DRAM banks composed of four 72-pin SIMM sockets that
support 4/8/16/32-MB 60/70ns SIMMs
•16-KB internal cache and 256-KB write-back second-level cache
•128-KB Flash ROM for system and VGA BIOS
•Two PCI enhanced IDE interfaces that support up to four IDE
devices
•System clock/calendar with 128 bytes CMOS RAM
•Cirrus 5430/5434/5440 VGA PCI accelerator that supports up to
2-MB video memory for a resolution up to 1280x1024 with 256
colors non-interlaced or 1024x768 with 65,536 colors interlaced
•External ports:
•PS/2 keyboard/mouse ports
•Two buffered high-speed serial ports
•One ECP/EPP high-speed parallel port
•Video port
•Feature socket for multimedia or Ethernet solution (optional)
•RJ-45 phone jack (optional)

System Board 1-3
1.1.1 Layout
Figure 1-1 shows the locations of the system board major
components.
1 Keyboard controller
2 Feature socket for multimedia
or Ethernet solution (optional)
3 Flash memory BIOS
4 Real-time clock
5 Slot board connector
6 Voltage regulator
7 Second-level cache
8 SIMM sockets
9 320-pin ZIF CPU socket
10 Video memory chips
11 Video memory upgrade sockets
12 Video port
13 Parallel port
14 COM2
15 COM1
16 PS/2 Mouse connector
17 PS/2 keyboard connector
18 RJ-45 phone jack (optional)
Figure 1-1 System Board Layout

1-4 User’s Guide
1.1.2 Slot Board
The system board comes with a slot board already installed. The slot
board carries the PCI and ISA bus slots for system enhancements and
future expansion.
The slot board may vary in size and layout depending on your system
housing. Figures 1-2 to 1-5 show the four kinds of slot boards.
Figure 1-2 2-PCI/3-ISA Slot Board (for generic desktop systems)
Figure 1-3 2-PCI/3-ISA Slot Board (for Aspire desktop systems)

System Board 1-5
Figure 1-4 3-PCI/5-ISA Slot Board
(for generic mini-tower systems)
Figure 1-5 3-PCI/4-ISA Slot Board
(for Aspire mini-tower systems)

1-6 User’s Guide
1.2 Jumpers and Connectors
1.2.1 Jumper and Connector Locations
Figure 1-6 shows the jumper and connector locations on the system
board.
Figure 1-6 System Board Jumper and Connector Locations
Jumpers are prefixed “JP”. Connectors are
prefixed “CN”.
The blackened pin of a jumper represents
pin 1.

System Board 1-7
1.2.2 Jumper Settings
Table 1-1 lists the system board jumpers with their corresponding
settings and functions.
Table 1-1 System Board Jumper Settings
Jumper Setting Function
BIOS Type
JP1 1-21
2-3 For models with Acer BIOS For models with OEM BIOS
Password Check
JP2 1-2
2-31Check password
Bypass password
BIOS ROM Type
JP3 Open
1-2
2-31
For 29EE010 only
EPROM
Flash ROM (Intel 28F010, 28F001,
or 28F101)
Onboard SMC665/669
JP6 1-2
2-31Disabled Enabled
CPU Local Bus Clock
JP8 1-4
2-51
3-6
50 MHz (Pentium 75 MHz)
60 MHz (Pentium 90/120/150 MHz)
66 MHz (Pentium 100/133 MHz)
CPU Type
JP12 1-21
2-3 Intel P54C or AMD K5 Cyrix M1
When your Flash ROM is Intel 28F001 (JP3
is set to pins 2-3), refer to JP20 for the Flash
ROM control settings.
1Default setting

1-8 User’s Guide
Table 1-1 System Board Jumper Settings (continued)
Jumper Setting Function
CPU Voltage
JP13 1-21
2-3 3.3825V for VR and standard CPU type
3.5250V for VRE CPU type
CPU Core / Local Bus
Clock Ratio
JP14, JP18 1-21, 1-21
2-3, 1-2
1-2, 2-3
2-3, 2-3
Intel P54C M1 and K5
3/2 3/2, 2/2, 3/1
2/1 1/1
3/1 3/2, 2/2, 3/1
5/2 1/1
Reset Switch
JP15 1-2
2-31For suspend mode function
For reset function
CN1 Connector Type
JP16, JP17 1-21
2-3 Feature Connector I2C interface
HDD/FDD LED Control
JP19 Open1
Closed
Detects HDD accesses only
(for generic housings)
Detects HDD and FDD accesses
(for Aspire housings only)
Flash ROM Control
JP20 1-2
2-31
(For Intel 28F001 only)
Programming boot block
Normal work or programming blocks
other than boot blocks
The settings of JP8, JP13, JP14, and JP18
depend on the Pentium CPU type.
1Default setting

System Board 1-9
1.2.3 Connector Functions
Table 1-2 lists the different connectors on the system board and their
respective functions.
Table 1-2 Connector Functions
Connector Function
CN1 VGA feature connector
CN2 PCI IDE channel 1
CN3 PCI IDE channel 2
CN4 Diskette drive connector
CN5 Power connector
CN6 Multifunction connector
CN7 Multifunction connector
CN8 Hard disk LED connector
CN9 Reserved
CN10 Feature socket for multimedia or
Ethernet card
Figures 1-7 and 1-8 show the pin assignments of multifunction
connectors CN6 and CN7 respectively.
Figure 1-7 20-Pin Multifunction Connector (CN6)

1-10 User’s Guide
Figure 1-8 8-pin Multifunction Connector (CN7)
1.3 ESD Precautions
Always observe the following electrostatic discharge (ESD)
precautions before installing a system component:
1. Do not remove a component from its antistatic packaging until
you are ready to install it.
2. Wear a wrist grounding strap before handling electronic
components. Wrist grounding straps are available at most
electronic component stores.
Do not attempt the procedures described in
the following sections unless you are a
qualified technician.