IBM RT User's Setup Manual page 341

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