Acer M1A User manual
System Board
System Board 1-1
The M1A is a high-performance Pentium PCI-based system board
that supports the 64-bit Pentium microprocessor running at
75/90/100/120/133/150/166 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 100/120/132 MB per second transfer
rate in burst mode.
The board has two memory banks composed of two 72-pin SIMM
sockets each that support a maximum system memory of 128 MB
using 32-MB SIMMs. The onboard 1-MB video memory is
upgradable to 2 MB for a higher video resolution.
The system board features a slot for the PCI/ISA slot board and two
Mode 4 PCI enhanced IDE interfaces that support up to four IDE
devices. A 50-pin Fast SCSI-II interface with 10 MB/s transfer rate
come with the system board to connect SCSI devices.
Standard I/O features such as two serial ports (COM1, COM2), one
parallel port, a diskette drive interface, and PS/2 mouse and keyboard
connectors reside on the system board.
1-2 User’s Guide
1.1 Major Features
The system board has the following major features:
•Pentium 75/90/100/120/133/150/166 MHz CPU in an SPGA 296-
pin 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 (CPU)
•256-KB synchronous or asynchronous second-level cache
•128-KB Flash ROM for system BIOS and VGA BIOS
•EISA-type connector for the slot board that contains two PCI and
three ISA slots (for desktop housing) or three PCI and 5 ISA slots
(for minitower housing)
•Two Enhanced IDE interfaces that support up to
four IDE devices
•System clock/calendar with 128/256 bytes CMOS RAM
•External ports:
•PS/2 keyboard/mouse ports
•Two buffered high-speed serial ports
•One ECP/EPP high-speed parallel port
•Video port
•RJ-45 Ethernet connector
System Board 1-3
1.1.1 Layout
Figure 1-1 shows the locations of the system board major
components.
1 Keyboard controller
2 Real-time clock (RTC)
3 Flash ROM BIOS
4 Buzzer
5 Fan connectors
6 SIMM sockets
7 CPU socket
8 Synchronous cache (optional)
9 CPU voltage regulator
10 Asynchronous cache
11 VGA BIOS
1
12 Video upgrade sockets
13 Video RAM
14 Video port
15 Parallel port
16 COM 2
17 Slot board connector
18 COM 1
19 PS/2 mouse connector
20 PS/2 keyboard connector
21 RJ-45 connector
Figure 1-1 System Board Layout
1For SCSI models only
1-4 User’s Guide
1.1.2 Slot Board
The system board comes with a slot board already installed. The slot
board carries two PCI and three 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 and 1-3 show the two kinds of slot boards.
Figure 1-2 2-PCI/3-ISA Slot Board (for desktop systems)
Figure 1-3 3-PCI/5-ISA Slot Board (for minitower systems)
System Board 1-5
1.2 Jumpers and Connectors
1.2.1 Jumper and Connector Locations
Figure 1-4 shows the jumper and connector locations on the system
board.
Figure 1-4 System Board Jumper and Connector Locations
Jumpers are prefixed “JP”. Connectors are
prefixed “CN”.
The blackened pin of a jumper represents
pin 1.
1-6 User’s Guide
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 1-2
2-3 For models with Acer BIOS
For models with OEM BIOS
Password Security
JP2 1-2
2-3 Enable password
Disable password
CPU Bus Frequency
JP5 Open
1-2
2-3
50 MHz (Pentium 75 MHz)
60 MHz (Pentium 90/120/150 MHz)
66 MHz (Pentium 100/133/166
MHz)
CPU Voltage
JP7 1-2
2-3 VR (3.3V ± 5% - 0%)
VRE (3.45V ~ 3.6V)
Reserved
JP9 2-3* Fixed setting. Do not reconfigure.
Reserved
JP14 Open* Leave open. Do not reconfigure.
System Board 1-7
Table 1-1 System Board Jumper Settings (continued)
Jumper Setting Function
CPU Type
JX1, JP8
JX1, JP8
JP10
JP11
JP12
JP13
2-3, 1-2
2-3, 2-3
1-2, 1-2
1-2, 2-3
Intel P54C M1 K5
C/B=3/1
C/B=5/2
C/B=3/2 C/B=3/1 C/B=3/2, 3/3
C/B=2/1 C/B=2/1 C/B=1/1
On Off On
On Off On
On Off Off
On Off On
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
CN4 Attachment Unit Interface (AUI)
CN5 Feature connector
CN6 Diskette drive connector
CN7 Enhanced IDE 2
CN8 Enhanced IDE 1
CN9 Power connector
CN10 SCSI connector
CN11 Power LED connector
CN12 Multifunction connector
1-8 User’s Guide
Table 1-2 Connector Functions (continued)
Connector Function
CN13 HDD LED connector
CN14 Speaker connector
CN15 Multifucntion connector
CN16 Buzzer (pins 1-2)
Speaker (pins 2-3)
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.
System Board 1-9
1.4 Memory Upgrade
The system board comes with four 72-pin SIMM sockets that support
4-MB and 16-MB single-density SIMMs as well as 8-MB and 32-MB
double-density SIMMs. When using 32-MB SIMMs, the sockets
support a maximum system memory of 128 MB. Table 1-3 lists the
possible memory configurations.
1.4.1 Rules for Adding Memory
•Use only one type of SIMM in a given bank.
•You may combine different types of SIMMs for a memory
configuration as long as the SIMMs in each bank are of the same
type.
•Always install SIMMs in pairs. For example, for a total memory
of 8 MB, install two 4-MB SIMMs into the sockets marked S5 and
S4 (bank 0) or S3 and S2 (bank 1). You can not use an 8-MB
SIMM alone for an 8-MB memory.
1-10 User’s Guide
1.4.2 Memory Configurations
Table 1-3 Memory Configurations
Bank 0 Bank 1 Total
S5 S4 S3 S2 Memory
4 MB 4 MB 8 MB
4 MB 4 MB 8 MB
8 MB 8 MB 16 MB
8 MB 8 MB 16 MB
4 MB 4 MB 4 MB 4 MB 16 MB
4 MB 4 MB 8 MB 8 MB 24 MB
8 MB 8 MB 4 MB 4 MB 24 MB
8 MB 8 MB 8 MB 8 MB 32 MB
16 MB 16 MB 32 MB
16 MB 16 MB 32 MB
4 MB 4 MB 16 MB 16 MB 40 MB
16 MB 16 MB 4 MB 4 MB 40 MB
8 MB 8 MB 16 MB 16 MB 48 MB
16 MB 16 MB 8 MB 8 MB 48 MB
16 MB 16 MB 16 MB 16 MB 64 MB
32 MB 32 MB 64 MB
32 MB 32 MB 64 MB
4 MB 4 MB 32 MB 32 MB 72 MB
32 MB 32 MB 4 MB 4 MB 72 MB
8 MB 8 MB 32 MB 32 MB 80 MB
32 MB 32 MB 8 MB 8 MB 80 MB
16 MB 16 MB 32 MB 32 MB 96 MB
32 MB 32 MB 16 MB 16 MB 96 MB
32 MB 32 MB 32 MB 32 MB 128 MB
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