SC486DX Motherboard Settings and Configuration

Processor	80486DX
Processor Speed	33MHz
Chip Set	OPTI
Max. Onboard DRAM	32MB
Cache	64/256KB
BIOS	Award
Dimensions	350mm x 125mm
I/O Options	Bus mouse port, floppy drive interface, IDE interface, parallel port, serial ports (2)
NPU Options	None

CONNECTIONS
Purpose	Location	Purpose	Location
Auxiliary keyboard	CN1	IDE interface	CN9
Power LED & keylock	CN2	Parallel port	CN10
Speaker	CN3	External battery	CN11
Reset switch	CN4	Serial port 1	CN12
IDE interface LED	CN5	Bus mouse port	CN13
Turbo switch	CN6	Serial port 2	CN14
Turbo LED	CN7	Floppy drive interface LED	LED
Floppy drive interface	CN8

USER CONFIGURABLE SETTINGS
Function		Jumper	Position
»	Bus speed select ATCLK/4 (5.5 MHz)	JP1	Closed
	Bus speed select ATCLK/6 (8.5 MHz)	JP1	Open
»	Factory configured - do not alter (selects iOSC/2)	JP5	pins 2 & 3 closed
»	Watchdog Timer mode select system reset after time-out	JP9	pins 1 & 2 closed
	Watchdog Timer mode select low IOCHK# NMI after time-out	JP9	pins 2 & 3 closed
	Watchdog Timer mode select disabled	JP9	Open
»	Floppy drive interface enabled	JP10	pins 1 & 2 closed
	Floppy drive interface disabled	JP10	pins 2 & 3 closed
»	Hard drive controller enabled or installed	JP11	pins 2 & 3 closed
	Hard drive access disabled	JP11	pins 1 & 2 closed
»	IDE interface enabled	JP12	pins 1 & 2 closed
	IDE interface disabled	JP12	pins 2 & 3 closed
»	Bus mouse interrupt select IRQ5	JP13	pins 1 & 2 closed
	Bus mouse interrupt select IRQ4	JP13	pins 3 & 4 closed
	Bus mouse interrupt select IRQ3	JP13	pins 5 & 6 closed
	Bus mouse interrupt select IRQ9	JP13	pins 7 & 8 closed
	Bus mouse interrupt select none (disabled)	JP13	Open
»	CMOS memory normal operation	JP14	pins 1 & 2 closed
	CMOS memory clear	JP14	pins 2 & 3 closed
»	Serial port 1 select COM1 (I/O address 3F8-3FFh)	JP15	pins 1 & 2 closed
	Serial port 1 select COM3 (I/O address 3E8-3EFh)	JP15	pins 2 & 3 closed
»	Serial port 1 enabled	JP16	pins 1 & 2 closed
	Serial port 1 disabled	JP16	pins 2 & 3 closed
»	Parallel port enabled	JP17	pins 1 & 2 closed
	Parallel port disabled	JP17	pins 2 & 3 closed
»	Serial port 2 enabled	JP18	pins 1 & 2 closed
	Serial port 2 disabled	JP18	pins 2 & 3 closed
»	Serial port 2 select COM2 (I/O address 2F8-2FFh)	JP19	pins 1 & 2 closed
	Serial port 2 select COM4 (I/O address 2E8-2EFh)	JP19	pins 2 & 3 closed
»	Bus mouse port enabled	JP20	pins 1 & 2 closed
	Bus mouse port disabled	JP20	pins 2 & 3 closed
»	Serial port 2 interrupt select IRQ3	JP21	pins 1 & 2 closed
	Serial port 2 interrupt select IRQ4	JP21	pins 2 & 3 closed
»	Serial port 1 interrupt select IRQ4	JP22	pins 1 & 2 closed
	Serial port 1 interrupt select IRQ3	JP22	pins 2 & 3 closed
»	Parallel port interrupt select IRQ7 (LPT1)	JP23	pins 1 & 2 closed
	Parallel port interrupt select IRQ5 (LPT2)	JP23	pins 2 & 3 closed
»	Parallel port select LPT1 (I/O address 378-37Fh)	JP24	pins 1 & 2 closed
	Parallel port select LPT2 (I/O address 278-27Fh)	JP24	pins 2 & 3 closed
»	Watchdog Timer interval select 500ms	JP25	Closed
	Watchdog Timer interval select 1 second	JP25	Open
»	Monitor type select color	JP26	Closed
	Monitor type select monochrome	JP26	Open

DRAM CONFIGURATION
Size	Bank 0	Bank 1
1MB	(4) 256K x 9	NONE
2MB	(4) 256K x 9	(4) 256K x 9
4MB	(4) 1M x 9	NONE
5MB	(4) 256K x 9	(4) 1M x 9
8MB	(4) 1M x 9	(4) 1M x 9
16MB	(4) 4M x 9	NONE
20MB	(4) 4M x 9	(4) 1M x 9
20MB	(4) 1M x 9	(4) 4M x 9
32MB	(4) 4M x 9	(4) 4M x 9

CACHE CONFIGURATION
Size	Bank 0	TAG (U31)
64KB	(8) 8K x 8	(1) 8K x 8
256KB	(8) 32K x 8	(1) 32K x 8
Note:The location of the TAG is unidentified and may not be present on some revisions.

CACHE JUMPER CONFIGURATION
Size	JP2	JP3	JP4
64KB	Open	Open	Open
256KB	Closed	Closed	Closed

CPU TYPE CONFIGURATION
Type	JP6	JP7	JP8
80486SX	Open	N/A	pins 2 & 3 closed
80487SX	Closed	pins 2 & 3 closed	pins 1 & 2 closed
80486DX	Closed	pins 1 & 2 closed	pins 1 & 2 closed