IBM 5160  -  Motherboard Switch Settings

On versus off

For switches, some people are unsure about which position is on and which position is off.
If you are unsure, then click here to see examples.

Switch block SW1

These settings apply to both versions of the 5160 motherboard, and apply to all three BIOS revisions for the 5160.

Switch 1:   ON : Normal setting
 OFF: Continously perform the Power On Self Test (POST)
Switch 2:   ON : 8087 math coprocessor chip is installed           ( IC socket U4, adjacent to power connectors)
 OFF: 8087 math coprocessor chip is not installed
Switches 3 and 4:   Installed motherboard RAM.
 3=ON , 4=ON: Only bank 0 populated
 3=OFF, 4=ON : Only banks 0/1 populated
 3=ON , 4=OFF: Only banks 0/1/2 populated
 3=OFF, 4=OFF: Banks 0/1/2/3 populated
Switches 5 and 6:   Video card type.
 5=OFF, 6=OFF: MDA (monochrome)
 5=OFF, 6=ON : CGA, at 40 column by 25 line mode
 5=ON , 6=OFF: CGA, at 80 column by 25 line mode
 5=ON , 6=ON: Cards with a BIOS expansion ROM (e.g. EGA / PGA / VGA)
Switches 7 and 8:   Floppy drive count.
 7=ON , 8=ON: 1 floppy drive
 7=OFF, 8=ON : 2 floppy drives
 7=ON , 8=OFF: 3 floppy drives
 7=OFF, 8=OFF: 4 floppy drives