Epson Apex 20020 - Manual (Page 125)

The table below shows the functions for the jumpers on the
memory card.
Memory card jumper settings
Jumper number Function
1 2 3
A A 640KB *
B A 512KB (disable upper 128KB)
B B 256KB (disable upper 384KB)
A Select EPROM size 27128*
B Select EPROM size 27256
l
Default setting
To access the memory card jumpers, you need to remove the
card from the computer first:
1. Remove the retaining screw from the bracket on the
memory card, as shown below.
Installing Option Cards 5-9