IBM RT PC Options Installation page 173

Use this table to set the switches if any of the following conditions are
present:
• The mM Personal Computer Display (5151) is attached to the
Enhanced Graphics Adapter.
• The mM Personal Computer Display (5151) is assigned to the AT
Coprocessor Adapter in
dedicated
mode.
• Another display is also installed and assigned to the AT Coprocessor
Adapter in dedicated mode.
Second Display
IBM 5151 Display Mode of
Assignment Operation Swl Sw2 Sw3 Sw4
Primary 80 X 25 Color Off Off On Off
Primary 40 X 25 Color On Off On Off
Secondary 80 X 25 Color Off On Off On
Secondary 40 X 25 Color On On Off On
7 -8 Options Installation