Precision 486SX/25, 486DX/33, 486DX2/50 Motherboard Settings and Configuration

Processor	80486SX/80487SX/80486DX/80486DX2
Processor Speed	25/33/50MHz
Chip Set	OPTI
Max. Onboard DRAM	64MB
Cache	64/256KB
BIOS	AMI
Dimensions	330mm x 218mm
I/O Options	Bus mouse port, floppy interface, IDE interface, parallel port, proprietary expansion module, serial ports (2), VGA port
NPU Options	None

CONNECTIONS
Purpose	Location	Purpose	Location
Internal battery holder	BAT	Serial port 1	J10
Proprietary expansion module	EXP	IDE interface LED	J23
Bus mouse	J1	Reset switch	J24
IDE interface	J5	Speaker	J25
Floppy drive interface	J6	Power LED & keylock	J26
Parallel port	J8	VGA port	J27
Serial port 2	J9

USER CONFIGURABLE SETTINGS
Function		Jumper	Position
»	Monitor type select color or monochrome VGA	W1	pins 1 & 2 closed
	Monitor type select monochrome	W1	pins 2 & 3 closed
»	CMOS memory normal operation	W2	pins 1 & 2 closed
	CMOS memory clear	W2	pins 2 & 3 closed
»	CPU clock source select SYSCLK/1	W3	pins 1 & 2 closed
	CPU clock source select SYSCLK/2	W3	pins 2 & 3 closed
»	VGA port enabled	W10	pins 1 & 2 closed
	VGA port disabled	W10	pins 2 & 3 closed

DRAM CONFIGURATION
Size	Bank 0	Bank 1	Bank 2	Bank 3
1MB	(1) 256K x 36	NONE	NONE	NONE
2MB	(1) 256K x 36	(1) 256K x 36	NONE	NONE
3MB	(1) 256K x 36	(1) 256K x 36	(1) 256K x 36	NONE
4MB	(1) 256K x 36	(1) 256K x 36	(1) 256K x 36	(1) 256K x 36
4MB	(1) 1M x 36	NONE	NONE	NONE
5MB	(1) 1M x 36	(1) 256K x 36	NONE	NONE
6MB	(1) 1M x 36	(1) 256K x 36	(1) 256K x 36	NONE
8MB	(1) 1M x 36	(1) 1M x 36	NONE	NONE
9MB	(1) 1M x 36	(1) 1M x 36	(1) 256K x 36	NONE
10MB	(1) 1M x 36	(1) 1M x 36	(1) 256K x 36	(1) 256K x 36
12MB	(1) 1M x 36	(1) 1M x 36	(1) 1M x 36	NONE
16MB	(1) 1M x 36	(1) 1M x 36	(1) 1M x 36	(1) 1M x 36
16MB	(1) 4M x 36	NONE	NONE	NONE
17MB	(1) 4M x 36	(1) 256K x 36	NONE	NONE
18MB	(1) 4M x 36	(1) 256K x 36	(1) 256K x 36	NONE
20MB	(1) 4M x 36	(1) 1M x 36	NONE	NONE
24MB	(1) 4M x 36	(1) 1M x 36	(1) 1M x 36	NONE
32MB	(1) 4M x 36	(1) 4M x 36	NONE	NONE
33MB	(1) 4M x 36	(1) 4M x 36	(1) 256K x 36	NONE
34MB	(1) 4M x 36	(1) 4M x 36	(1) 256K x 36	(1) 256K x 36
36MB	(1) 4M x 36	(1) 4M x 36	(1) 1M x 36	NONE
40MB	(1) 4M x 36	(1) 4M x 36	(1) 1M x 36	(1) 1M x 36
48MB	(1) 4M x 36	(1) 4M x 36	(1) 4M x 36	NONE
64MB	(1) 4M x 36	(1) 4M x 36	(1) 4M x 36	(1) 4M x 36

CACHE CONFIGURATION
Size	Bank 0
64KB	(8) 8K x 8
256KB	(8) 32K x 8

CACHE JUMPER CONFIGURATION
Size	W4	W5	W9
64KB	pins 2 & 3 closed	pins 2 & 3 closed	pins 2 & 3 closed
256KB	pins 1 & 2 closed	pins 1 & 2 closed	pins 1 & 2 closed

CPU TYPE CONFIGURATION
Type	W6	W7	W8
80486SX	pins 2 & 3 closed	pins 2 & 3 closed	Open
80487SX	pins 1 & 2 closed	pins 1 & 2 closed	pins 1 & 2 closed
80486DX	pins 1 & 2 closed	pins 1 & 2 closed	pins 2 & 3 closed

VGA REFRESH CONFIGURATION (800 X 600 RESOLUTION)
Refresh Rate		SW1/1	SW1/2
	56Hz	Off	Off
	56Hz	On	On
»	60Hz	Off	On
	72Hz	On	Off

VGA REFRESH CONFIGURATION (1024 X 768 RESOLUTION)
Refresh Rate		SW1/3	SW1/4
»	Interlaced	Off	Off
	60Hz	Off	On
	70Hz	On	Off
	72Hz	On	On

VGA REFRESH CONFIGURATION
Refresh Rate		SW1/5
»	31.5Hz horizontal, 60/70Hz vertical	Off
	40Hz horizontal, 75/80Hz vertical (see note)	On
	Note :Use 75Hz for video modes 0 through 10h and 13h. Use 80Hz for video modes 11h and 12h.

VRAM CONFIGURATION
Size		Bank 0
»	512KB	NONE
	1MB	(4) 44256 ZIPPs

VRAM SWITCH CONFIGURATION
Size		SW1/6
»	512KB	On
	1MB	Off