ORCA (REV. B) Motherboard Settings and Configuration

Processor	CX486/AM486/80486SX/SL80486/80486DX/80486DX4/P24D/P24T
Processor Speed	25/33/40/50(internal)/50/66(internal)100(internal)MHz
Chip Set	OPTI
Video Chip Set	Cirrus Logic
Maximum Onboard Memory	128MB
Maximum Video Memory	2MB
Cache	64/128/256/512KB
BIOS	Unidentified
Dimensions	Unidentified
I/O Options	Floppy drive interface, IDE interface, parallel port, PS/2 mouse port, serial ports (2), VGA port
NPU Options	None

CONNECTIONS
Purpose	Location	Purpose	Location
IDE interface	J2	Auxiliary keyboard connector	J14
Floppy drive interface	J3	PS/2 mouse port	J21
Parallel port	J4	Reset switch	J22
Serial port 1	J5	Speaker	J25
Serial port 2	J6	Chassis fan power	J26
IDE interface LED	J9	VGA port	J33

USER CONFIGURABLE SETTINGS
Function		Label	Position
	IDE IRQ14 enabled	J1	Closed
	IDE IRQ14 disabled	J1	Open
	IDE read prefetch enabled	J8	Pins 1 & 2 closed
	IDE read prefetch disabled	J8	Pins 2 & 3 closed
	IDE type select primary	J11	Pins 1 & 3 closed
	IDE type select secondary	J11	Pins 3 & 5 closed
	IDE interface enabled	J11	Pins 2 & 4 closed
	IDE interface disabled	J11	Pins 4 & 6 closed
»	Factory configured - do not alter	J12	Open
	Floppy drive select 1.44MB	J13	Pins 1 & 2 closed
	Floppy drive select 2.88MB	J13	Pins 3 & 4, 5 & 6 closed
»	CMOS memory normal operation	J17	Pins 2 & 3 closed
	CMOS memory clear	J17	Pins 1 & 2 closed
	PS/2 mouse IRQ12 enabled	J18	Closed
	PS/2 mouse IRQ12 disabled	J18	Open
	Password enabled	J19	Closed
	Password disabled	J19	Open
	Video IRQ9 enabled	J31	Closed
	Video IRQ9 disabled	J31	Open
»	Factory configured - do not alter	J38	Unidentified

DRAM CONFIGURATION
Size	Bank 0	Bank 1	Bank 2	Bank 3
4MB	(1) 1M x 36	None	None	None
8MB	(1) 2M x 36	None	None	None
8MB	(1) 1M x 36	(1) 1M x 36	None	None
16MB	(1) 4M x 36	None	None	None
16MB	(1) 2M x 36	(1) 2M x 36	None	None
16MB	(1) 1M x 36	(1) 1M x 36	(1) 1M x 36	(1) 1M x 36
24MB	(1) 2M x 36	(1) 2M x 36	(1) 1M x 36	(1) 1M x 36
32MB	(1) 8M x 36	None	None	None
32MB	(1) 4M x 36	(1) 4M x 36	None	None
32MB	(1) 2M x 36	(1) 2M x 36	(1) 2M x 36	(1) 2M x 36
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) 2M x 36	(1) 2M x 36
64MB	(1) 8M x 36	(1) 8M x 36	None	None
64MB	(1) 4M x 36	(1) 4M x 36	(1) 4M x 36	(1) 4M x 36
72MB	(1) 8M x 36	(1) 8M x 36	(1) 1M x 36	(1) 1M x 36
80MB	(1) 8M x 36	(1) 8M x 36	(1) 2M x 36	(1) 2M x 36
96MB	(1) 8M x 36	(1) 8M x 36	(1) 4M x 36	(1) 4M x 36
128MB	(1) 16M x 36	(1) 16M x 36	None	None
128MB	(1) 8M x 36	(1) 8M x 36	(1) 8M x 36	(1) 8M x 36

CACHE CONFIGURATION

Note: Board accepts 64KB/128KB/256KB/512KB cache. The location of banks 0 & 1 is unidentified.

CACHE JUMPER CONFIGURATION
Size	J15
64KB	Open
128KB	Pins 5 & 6 closed
256KB	Pins 3 & 4, 5 & 6 closed
512KB	Pins 1 & 2, 3 & 4, 5 & 6 closed

CACHE BANK CONFIGURATION
Setting	J16
Single bank	Pins 1 & 2 closed
Dual banks	Pins 2 & 3 closed

VIDEO MEMORY CONFIGURATION

Note: Board accepts up to 2MB of video memory. The location and chip sizes are unidentified.

CPU SPEED SELECTION
Speed	J7	J28
25MHz	Pins 1 & 3, 2 & 4 closed	Pins 5 & 6 closed
33MHz	Pins 1 & 3, 4 & 6 closed	Pins 1 & 2, 5 & 6 closed
40MHz	Pins 2 & 4, 3 & 5 closed	Pins 3 & 4, 5 & 6 closed
50iMHz	Pins 1 & 3, 2 & 4 closed	Pins 5 & 6 closed
50MHz	Pins 3 & 5, 4 & 6 closed	Pins 1 & 2, 3 & 4, 5 & 6 closed
66iMHz	Pins 1 & 3, 4 & 6 closed	Pins 1 & 2, 5 & 6 closed
100iMHz	Pins 1 & 3, 4 & 6 closed	Pins 1 & 2, 5 & 6 closed

CPU TYPE SELECTION
Type	J29	J37
Cyrix	Pins 2 & 3 closed	Pins 1 & 2, 3 & 4 closed
AMD	Pins 1 & 2 closed	Open
Intel	Pins 1 & 2 closed	Open

CPU TYPE SELECTION
Type	J36
Intel SX	Pins 2 & 3 closed
Intel DX	Pins 1 & 2, 3 & 4 closed

CPU TYPE SELECTION
Type	J24
SL80486	Pins 1 & 2, 3 & 4 closed
P24T burst	Pins 5 & 6 closed
P24T WB	Pins 7 & 8 closed
P24T WT	Open

CPU TYPE SELECTION
Type	J34
Cyrix	Pins 4 & 6 closed
SL80486	Pins 2 & 4 closed
P24D WB	Pins 3 & 5 closed
P24D WT	Pins 1 & 3 closed

CPU TYPE SELECTION
Type	J35
All CPU types	Pins 1 & 3 closed
P24T only	Pins 3 & 5 closed
Bit 0 to stop clock	Pins 2 & 4 closed
Bit 1 to stop clock	Pins 4 & 6 closed

CPU MULTIPLIER SELECTION
Multiplier	J23
Cyrix CPU	Pins 3 & 4 closed
2x	Pins 3 & 5 closed
2.5x	Pins 1 & 3 closed
3x	Open

CPU FREQUENCY SELECTION
Speed	J27
8MHz	Pins 1 & 2 closed
16MHz (DX4)	Pins 2 & 3 closed

DMA CHANNEL SELECTION
Channel	J32
1	Pins 3 & 4, 5 & 6 closed
3	Pins 1 & 2, 7 & 8 closed

IDE MODE SELECTION
Speed	J10
180ns	Pins 1 & 3, 2 & 4 closed
240ns	Pins 3 & 5, 2 & 4 closed
383ns	Pins 1 & 3, 4 & 6 closed
480ns	Pins 3 & 5, 4 & 6 closed

ON BOARD VIDEO SELECTION
Setting	J30	J39
Enabled	Pins 2 & 3 closed	Closed
Disabled	Pins 1 & 2 closed	Open