MICRONICS MOTHERBOARD

80486DX-25 and 33 EISA (Full size 09-00090-xx)

This document is for the full-sized (13.3" x 12.025") 80486DX-25, 80486DX-33 EISA

motherboard. The part number for this board is 09-00090-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.

The bus speed for this motherboard is fixed at 8MHz.

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+ MOTHERBOARD SWITCH SETTINGS +

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+ * = Default setting +

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SW1

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1 External cache not invalidated *Off

External cache invalidated On

2 On board Bios enabled *Off

On board Bios disabled On

3 64K external cache Off

128K or 256K external cache On

4 33MHz system Off

25MHz system On

5 Reserved *Off

6 Reserved *Off

7 CGA / EGA / VGA On

Monochrome Off

8 128K external cache On

64K or 256K external cache Off

SW2

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1 Memory settings (see below)

2 Memory settings (see below)

3 Memory settings (see below)

4 Memory settings (see below)

5 Memory settings (see below)

6 Cache video Bios *Off

Don't cache video Bios On

7 Cache D00000-EFFFFF region *On

Don't cache D00000-EFFFFF Off

8 Reserved *Off

DIP switch settings for memory size

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Memory Banks DIP Switch 2

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MB 0 1 2 3 S1 S2 S3 S4 S5

---- ---- ---- ---- ---- ---- ---- ---- ---- ----

4MB 1MB ON ON ON ON ON

8MB 1MB 1MB OFF ON ON ON ON

12MB 1MB 1MB 1MB ON OFF ON ON ON

16MB 1MB 1MB 1MB 1MB OFF OFF ON ON OFF

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, 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

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+ +

+ MOTHERBOARD JUMPER SETTINGS +

+ +

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J2 Keyboard connector

Pin 1 - Keyboard clock

Pin 2 - Keyboard data

Pin 3 - no connector

Pin 4 - Ground

Pin 5 - +5 volts DC

J3 External 6-volt battery connector

Pin 1 - Battery Positive

Pin 2 - no connector

Pin 3 - Ground

Pin 4 - Ground

J15 External speaker

Pin 1 - Speaker

Pin 2 - no connector

Pin 3 - Ground

Pin 4 - +5 volts DC

J16 Keylock / Power LED

Pin 1 - Power LED signal

Pin 2 - no connector

Pin 3 - Ground

Pin 4 - Keyboard lock signal

Pin 5 - Ground

W3 External cache configuration

Pins 1-2 64K or 128K

Pins 2-3 256K

W4 External cache configuration

Pins 1-2 64K

Pins 2-3 128K or 256K

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