Onboard System Memory Size; Figure 2-5: Ram Banks & Jumpers For Bank Selection - Datatech Enterprises Apex 386SX/20 User Manual

Onboard System Memory Size

Jumpers W1- W6 are used to set the RAM size you want on the
mainboard. The DIP and SIMM DRAM banks can contain from 512KB,
640KB, 1 MB, 1.5MB, 2MB, 3MB, 4MB to 5MB by means of setting
jumpers W1 - W6. Refer to Figure 2-5 below for the location of jumpers
W1 - W6 and the RAM banks.
Figure 2-5: RAM Banks & Jumpers for Bank Selection
8 Chapter 2: Setting Up Your System