|Switch 1:|| ON : 5150 has no floppy drives
OFF: 5150 has one or more floppy drives
|The ON setting was used for the floppyless 5150s that IBM supplied|
|Switch 2:|| ON : 8087 math coprocessor chip is not installed
OFF: 8087 math coprocessor chip is installed
|Sits in IC socket U4, adjacent to keyboard connector J7|
|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)
ON/ON setting is only applicable to the 10/27/82 dated BIOS revision
|Switches 7 and 8:|| Floppy drive count. Used if switch 1 is OFF.
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