Device Switch's On / Off Function 
POST 1 On POST loop test 
POST 1 Off Normal position  
Coprocessor 2 Off Coprocessor installed 
Coprocessor 2 On Coprocessor NOT installed 
Memory 3 On / 4 On 256 KB RAM 
Memory 3 Off / 4 On 512 KB RAM 
Memory 3 Off / 4 Off 640 KB RAM 
Video 5 On / 6 On EGA / VGA 
Video 5 Off / 6 Off Monochrome 
Video 5 On / 6 Off CGA 80x25 mode 
Video 5 Off / 6 On CGA 40x25 mode  
Floppy Drives 7 On / 8 On 1 Floppy Drive present 
Floppy Drives 7 Off / 8 On  2 Floppy Drives present 
Floppy Drives 7 On / 8 Off  3 Floppy Drives present 
Floppy Drives 7 Off / 8 Off  4 Floppy Drives present