486DX-25/33, 486SX-20 Motherboard Settings and Configuration

Processor	80486SX/80486DX
Processor Speed	20/25/33MHz
Chip Set	Peaktron
Max. Onboard DRAM	32MB
Cache	None
BIOS	AMI
Dimensions	330mm x 218mm
I/O Options	None
NPU Options	None

CONNECTIONS
Purpose	Location	Purpose	Location
Reset switch	J1	Speaker	J4
Turbo switch	J2	Power LED & Keylock	J5
Turbo LED	J3	External battery	JP4

USER CONFIGURABLE SETTINGS
Function		Jumper/Switch	Position
»	Parity check enabled	J6	Closed
	Parity check disabled	J6	Open
»	Factory configured - do not alter	J8	N/A
»	Monitor type select monochrome	J10	Open
	Monitor type select color	J10	Closed
»	CPU speed select switchable at turbo switch	JP1	pins 1 & 2 closed
	CPU speed select forced fast	JP1	pins 2 & 3 closed
	CPU speed select forced slow	JP1	Open
»	Factory configured - do not alter	JP5	N/A
»	20/25MHz CPU using 70ns DRAM or33MHz CPU using 60ns	JP6	Open
	20/25MHz CPU using 60ns DRAM	JP6	Closed
»	Shadow BIOS disabled	SW1/5	Closed
	Shadow BIOS enabled	SW1/5	Open
»	Bus speed select ATCLK/3	SW1/6	Open
	Bus speed select ATCLK/4	SW1/6	Closed
Note:Location of JP6 is unverified. If using 8 bit SIMMs, J6 must be 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) 1M x 9	(4) 4M x 9
32MB	(4) 4M x 9	(4) 4M x 9

DRAM JUMPER CONFIGURATION
Size	SW1/1	SW1/2	SW1/3	SW1/4
1MB	Closed	Open	Open	Closed
2MB	Open	Open	Open	Closed
4MB	Closed	Closed	Open	Open
5MB	Open	Closed	Open	Closed
8MB	Open	Closed	Open	Open
16MB	Closed	Open	Open	Open
20MB	Open	Open	Closed	Open
32MB	Open	Open	Open	Open

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

BIOS CONFIGURATION
Type	J7	J9
27256	Open	pins 1 & 2 closed
27512	Closed	pins 2 & 3 closed