STC-SIS486C-DX/SX Motherboard Settings and Configuration

Processor	80486SX/80487SX/80486DX
Processor Speed	20/25/33/50MHz
Chip Set	SIS
Max. onboard DRAM	32MB
Cache	32/64/128/256KB
BIOS	AMI
Dimensions	218mm x 218mm
I/O Options	None
NPU Options	None

CONNECTIONS
Purpose	Location	Purpose	Location
External battery	J1	Turbo LED	J6
Power LED & keylock	J3	Turbo switch	J7
Speaker	J4	Reset switch	J8
Unknown	J5

USER CONFIGURABLE SETTINGS
Function		Jumper	Position
»	CMOS memory normal operation (internal battery)	J1	pins 2 & 3 closed
	CMOS memory normal operation (external battery)	J1	pins 1 & 4 closed
	CMOS memory clear	J1	Open
»	Monitor type select color	J2	Closed
	Monitor type select monochrome	J2	Open
»	CPU speed select iOSC/1	J9	pins 1 & 2 closed
	CPU speed select iOSC/2	J9	pins 2 & 3 closed
»	Turbo switch enabled	J10	Closed
	Turbo switch disabled	J10	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
8MB	(4) 1M x 9	(4) 1M x 9
16MB	(4) 4M x 9	NONE
20MB	(4) 1M x 9	(4) 4M x 9
32MB	(4) 4M x 9	(4) 4M x 9

CACHE CONFIGURATION
Size	Bank 0 (U26 - 29)	Bank 1 (U22 - U25)	Tag	Dirty Bit
32KB	(4) 8K x 8	NONE	8K x 8	16K x 4
64KB	(4) 8K x 8	(4) 8K x 8	8K x 8	16K x 4
128KB	(4) 32K x 8	NONE	32K x 8	16K x 4
256KB	(4) 32K x 8	(4) 32K x 8	32K x 8	16K x 4

CACHE JUMPER CONFIGURATION
Size	J11	J12	J13	J14	J15	J16	J17	J18	J19
32KB	1 & 2	Open	1 & 2	1 & 2	1 & 2	1 & 2	1 & 2	1 & 2	1 & 2
64KB	2 & 3	Open	1 & 2	2 & 3	1 & 2	1 & 2	2 & 3	1 & 2	1 & 2
128KB	1 & 2	1 & 2	2 & 3	2 & 3	2 & 3	1 & 2	2 & 3	2 & 3	1 & 2
256KB	2 & 3	2 & 3	2 & 3	2 & 3	2 & 3	2 & 3	2 & 3	2 & 3	2 & 3
Note:Pins designated should be in the closed position.

CPU TYPE CONFIGURATION
Type	J20	J21	J22
80486SX	Closed	pins 1 & 2 closed	pins 1 & 2 closed
80487SX	Closed	pins 1 & 2 closed	pins 2 & 3 closed
80486DX	Open	pins 2 & 3 closed	Open