This document is for the full-sized (13.3" x 12.025") 80486DX-33, 80486DX-50, and
80486DX2-66 EISA motherboard. The part number for this board is 09-00117-xx.
It's identifying features are: an LED between expansion slots #5 and #6; eight 32-bit
expansion slots; sixteen sockets for SIMMs (four banks of 4); a socket for a Weitek 4167
coprocessor; one proprietary 32-bit slot which accommodates the MVC32LB (a video card
based on the ATI Mach 32 chip).
The bus speed for this motherboard is fixed at 8MHz.
+=============================+
+ +
+ MOTHERBOARD SWITCH SETTINGS +
+ +
+ * = Default setting +
+=============================+
1 Memory size (see below)
2 Memory size (see below)
3 Memory size (see below)
4 Memory size (see below)
5 Memory size (see below)
6 Reserved *On
7 Reserved *Off
8 Color video adapter *On
Mono video adapter Off
DIP switch settings for memory size
===================================
Memory Banks DIP Switch 2
---------------------------------------------------
MB 0 1 2 3 S1 S2 S3 S4 S5
---- ---- ---- ---- ---- ---- ---- ---- ---- ----
1MB 256K ON ON ON ON ON
2MB 256K 256K OFF ON ON ON ON
3MB 256K 256K 256K ON OFF ON ON ON
4MB 256K 256K 256K 256K OFF OFF ON ON ON
4MB 1MB ON ON OFF ON ON
5MB 256K 1MB ON ON OFF OFF ON
6MB 256K 256K 1MB ON OFF ON OFF ON
7MB 256K 256K 256K 1MB OFF ON ON OFF ON
8MB 1MB 1MB OFF ON OFF ON ON
9MB 256K 1MB 1MB ON OFF OFF OFF ON
10MB 256K 256K 1MB 1MB OFF OFF ON OFF ON
12MB 1MB 1MB 1MB ON OFF OFF ON ON
13MB 256K 1MB 1MB 1MB OFF OFF OFF OFF ON
16MB 1MB 1MB 1MB 1MB OFF OFF OFF ON ON
16MB 4MB ON ON OFF ON OFF
20MB 1MB 4MB ON ON OFF OFF OFF
24MB 1MB 1MB 4MB ON OFF ON OFF OFF
28MB 1MB 1MB 1MB 4MB OFF ON ON OFF OFF
32MB 4MB 4MB OFF ON OFF ON OFF
36MB 1MB 4MB 4MB ON OFF OFF OFF OFF
40MB 1MB 1MB 4MB 4MB OFF OFF ON OFF OFF
48MB 4MB 4MB 4MB ON OFF OFF ON OFF
52MB 1MB 4MB 4MB 4MB OFF OFF OFF OFF OFF
64MB 4MB 4MB 4MB 4MB OFF OFF OFF ON OFF
In the table above, 256K indicates that four 256Kx9 SIMMs are installed in the bank,
1MB indicates that four 1Mx9 SIMMs are installed in the bank, and 4MB indicates that
four 4Mx9 SIMMs are installed in the bank. The above shows all of the possible memory
configurations.
When installing more than 16MB of memory, BIOS relocation must be disabled. Bios
relocation copies the video Bios (C0000-C7FFF) and the system ROM Bios (F0000-FFFFF) into
RAM. The motherboard adds 15MB to these addresses (F00000) to be able to differentiate
between the ROM and RAM. Enabling the relocation feature causes the memory above 16MB
to become non-contiguous and therefore inaccessible.
Micronics Computers has tested and verified the following memory brands:
Toshiba, Siemens, Mitsubishi, NEC
+=============================+
+ +
+ MOTHERBOARD JUMPER SETTINGS +
+ +
+=============================+
J2 Keyboard connector
Pin 1 - Keyboard clock
Pin 2 - Keyboard data
Pin 3 - no connector
Pin 4 - Ground
Pin 5 - +5 volts DC
J17 External 6-volt battery connector
Pin 1 - Battery Positive
Pin 2 - no connector
Pin 3 - Ground
Pin 4 - Ground
J22 External speaker
Pin 1 - Speaker
Pin 2 - no connector
Pin 3 - Ground
Pin 4 - +5 volts DC
J23 Keylock / Power LED
Pin 1 - Power LED signal
Pin 2 - no connector
Pin 3 - Ground
Pin 4 - Keyboard lock signal
Pin 5 - Ground
W5 Reset switch
Pin 1 - Signal
Pin 2 - Ground
W6 Turbo switch
Pin 1 - Signal
Pin 2 - Ground
W7 Turbo LED
Pin 1 - Signal
Pin 2 - Ground
W11 Reserved
Pins 2-3
W12 Reserved
Pins 1-2
W13 Floppy Drive
Pins 1-2 -- Enables on-board floppy drive
Pins 2-3 -- Disables on-board floppy drive
W45 Reserved
Pins 1-2
W43 CPU selection
Pins 1-2 486DX2-50
Not installed 486DX-33
NOTE: The system board is configured at the factory for either the 486DX-33 or the 486DX2-50.
It is not possible to switch the 486DX-33 to the 486DX2-50 (or vice versa) by
configuring the jumpers.
Serial Port configuration
=========================
I/O addresses
-------------
COM1 = 3F8-3FFh
COM2 = 2F8-2FFh
COM1 COM2 W2 W8 W9
------------------------------------
Enabled Enabled 1-2 1-2 1-2
Enabled Disabled 1-2 1-2 2-3
Disabled Enabled 2-3 1-2 1-2
Disabled Disabled 2-3 1-2 2-3
Parallel Port configuration
===========================
Port I/O address W3 W4 W10
---------------------------------------
LPT1 3BC-3BEh 1-2 2-3 2-3
LPT2 378-37Ah 1-2 1-2 2-3
LPT3 278-27Ah 2-3 1-2 2-3
Disabled 2-3 2-3 2-3
Cache configuration
===================
Cache W20 W21 W41 W44
----------------------------
64K N/C N/C N/C 2-3
256K 1-2 1-2 1-2 1-2
N/C = Not Connected