TURBO MAIN BOARD (426A) Motherboard Settings and Configuration

Processor	8088
Processor Speed	4.77/8MHz
Chip Set	Unidentified
Video Chip Set	None
Maximum Onboard Memory	640KB
Maximum Video Memory	None
Cache	None
BIOS	Unidentified
Dimensions	330mm x 218mm
I/O Options	None
NPU Options	8087

CONNECTIONS
Purpose	Location	Purpose	Location
Turbo switch (to turbo switch button)	JP5	Power LED	JP9 pins 3 & 4
Turbo LED	JP9 pins 1 & 2	Speaker	P4

USER CONFIGURABLE SETTINGS
Function		Label	Position
»	Factory configured - do not alter	JP1	Unidentified
	Turbo enabled	JP6	Closed
	Turbo disabled	JP6	Open
	Turbo enabled (CTRL, ALT, +)	JP7	Closed
	Turbo disabled (CTRL, ALT, -)	JP7	Open
	Keyboard lock disabled	JP8	Closed
	Keyboard lock enabled	JP8	Open
»	Factory configured - do not alter	SW1/1	Off
	NPU not installed	SW1/2	On
	NPU installed	SW1/2	Off
Note: JP6 is for turbo selectable through hardware. JP7 is for turbo selectable through software. Both jumpers cannot be closed at the same time.

DRAM CONFIGURATION
Size	Bank 0	Bank 1	Bank 2	Bank 3
256KB (A)	(9) 4164	(9) 4164	(9) 4164	(9) 4164
256KB (B)	(9) 41256	None	None	None
512KB	(9) 41256	(9) 41256	None	None
640KB	(9) 41256	(9) 41256	(9) 4164	(9) 4164
Note: The location of banks 0, 1, 2, & 3 are unidentified.

DRAM JUMPER CONFIGURATION
Size	JP3	JP4
256KB (A)	Pins 1 & 3, 5 & 7 closed	Pins 2 & 4 closed
256KB (B)	Pins 2 & 4, 6 & 8 closed	Pins 1 & 3 closed
512KB	Pins 2 & 4, 6 & 8 closed	Pins 1 & 3 closed
640KB	Pins 2 & 4, 6 & 8 closed	Pins 1 & 3 closed

DRAM SWITCH CONFIGURATION
Size	SW1/3	SW1/4
128KB	Off	On
192KB	On	Off
256KB	Off	Off

FLOPPY DRIVE SELECTION
Drives installed	SW1/7	SW1/8
1	On	On
2	Off	On
3	On	Off
4	Off	Off

MONITOR SELECTION
Type	SW1/5	SW1/6
None	On	On
Color (40 x 20)	Off	On
Color (80 x 25)	On	Off
Monochrome	Off	Off