This document is for the full-sized (13.8" x 12.025") 486-25 ISA motherboard.
The part number for this board is 09-00025-xx.
It's identifying features are: an LED between expansion slots #5 and #6; eight 16-bit
expansion slots; sixteen sockets for SIMMs (four banks of 4); a socket for a Weitek 4167
coprocessor.
The bus speed for this motherboard is fixed at 8MHz.
+=============================+
+ +
+ MOTHERBOARD SWITCH SETTINGS +
+ +
+ * = Default setting +
+=============================+
SW1
---
1 Internal cache enabled *On
Internal cache disabled Off
2 Enable on-board Bios *Off
Enable external Bios On
3 Reserved *On
4 External cache enabled *On
External cache disabled Off
5 Bios relocation enabled On
Bios relocation disabled *Off
6 Reserved *Off
7 CGA / EGA / VGA *On
Monochrome Off
8 Reserved *Off
SW2
---
1 Memory size (see below)
2 Memory size (see below)
3 Memory size (see below)
4 Memory size (see below)
5 Reserved *Off
6 D00000-EFFFFF cacheable *Off
D00000-EFFFFF non-cacheable On
7 64K or 256K external cache Off
128K external cache On
8 64K external cache Off
128K or 256K external cache On
DIP switch settings for memory size
===================================
Memory Banks DIP Switch 2
-----------------------------------------------
MB 0 1 2 3 S1 S2 S3 S4
---- ---- ---- ---- ---- ---- ---- ---- ----
1MB 256K ON ON ON ON
2MB 256K 256K OFF ON ON ON
3MB 256K 256K 256K ON OFF ON ON
4MB 256K 256K 256K 256K OFF OFF ON ON
4MB 1MB ON ON OFF ON
5MB 256K 1MB ON ON OFF OFF
6MB 256K 256K 1MB ON OFF ON OFF
7MB 256K 256K 256K 1MB OFF ON ON OFF
8MB 1MB 1MB OFF ON OFF ON
9MB 256K 1MB 1MB ON OFF OFF OFF
10MB 256K 256K 1MB 1MB OFF OFF ON OFF
12MB 1MB 1MB 1MB ON OFF OFF ON
13MB 256K 1MB 1MB 1MB OFF OFF OFF OFF
16MB 1MB 1MB 1MB 1MB OFF OFF OFF ON
In the table above, 256K indicates that four 256Kx9 SIMMs are installed in the bank,
and 1MB indicates that four 1Mx9 SIMMs are installed in the bank. The above shows
all of the possible memory configurations.
The maximum amount of memory supported by this board is 16MB.
Micronics Computers has tested and verified the following memory brands:
Toshiba, Siemens, Mitsubishi, NEC
+=============================+
+ +
+ MOTHERBOARD JUMPER SETTINGS +
+ +
+=============================+
J2 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
W2 Reserved
Pins 2-3
W4 Reset switch
Pin 1 - Signal
Pin 2 - Ground
W5 Turbo LED
Pin 1 - Signal
Pin 2 - Ground
W6 Turbo switch
Pin 1 - Signal
Pin 2 - Ground
W8 External cache configuration
Pins 1-2 - 64K
Pins 2-3 - 128K or 256K
W9 External cache configuration
Pins 1-2 - 64K or 128K
Pins 2-3 - 256K