IBM 5162 - Motherboard Switch/Jumper Settings
Display Switch (SW1)
This switch is used for selecting the video card type (MDA, CGA, EGA).
This jumper enables or disables the 128 KB of motherboard RAM that sits in the address space of 512K to 640K.
'Enabled' is the normal setting of the jumper (640 KB of conventional memory is better than 512 KB).
The 128 KB of RAM is made up of the six RAM chips that are located next to the motherboard's power connector.