OPTI 486-33 AT Motherboard Settings and Configuration

Processor	80486SX/80486DX
Processor Speed	20/25/33MHz
Chip Set	OPTI
Max. Onboard DRAM	32MB
Cache	64/128/256/512KB
BIOS	AMI/MR
Dimensions	330mm x 218mm
I/O Options	None
NPU Options	4167

CONNECTIONS
Purpose	Location	Purpose	Location
External battery	J1 pins 1 & 4	Turbo LED	J4
Power LED & keylock	J2	Turbo switch	J5
Speaker	J3	Reset switch	J6

USER CONFIGURABLE SETTINGS
Function		Jumper	Position
»	CMOS memory normal operation (internal battery)	J1	pins 2 & 3 closed
	CMOS memory normal operation (external battery)	J1	Closed
	CMOS memory clear	J1	pins 3 & 4 closed
»	Bus speed select iOSC/6	JP7	Open
	Bus speed select iOSC/8	JP7	Closed
»	Monitor type select color	JP12	Closed
	Monitor type select monochrome	JP12	Open

DRAM CONFIGURATION
Size	Bank 0	Bank 1
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	Bank 1	TAG (U41)	TAG (U57)
64KB	(8) 8K x 8	NONE	(1) 8K x 8	(1) 64K x 1
128KB	(8) 8K x 8	(8) 8K x 8	(1) 8K x 8	(1) 64K x 1
256KB	(8) 32K x 8	NONE	(1) 32K x 8	(1) 64K x 1
512KB	(8) 32K x 8	(8) 32K x 8	(1) 32K x 8	(1) 64K x 1

CACHE JUMPER CONFIGURATION
Size	JP6	JP8	JP9	JP10	JP11
64KB	pins 2 & 3 closed	Open	Open	Open	Open
128KB	pins 2 & 3 closed	Open	Closed	Open	Closed
256KB	pins 2 & 3 closed	Open	Closed	Closed	Closed
512KB	pins 1 & 2 closed	Closed	Closed	Closed	Closed

CPU TYPE CONFIGURATION
Type	JP2	JP3	JP4
80486SX	Open	pins 1 & 2 closed	Open
80486DX	pins 1 & 2 closed	pins 2 & 3 closed	Closed