IBM Personal Computer XT Manual To Operations page 222

Coprocessor
Switch 2 is set to indicate if the coprocessor is installed.
With Coprocessor
lD~DDODDD~
'\.
\
Without Copr
0 1 2 3 4 5 6 7 8
fD~DDDDDD
'\.
ocessor
\
\
Memory
The following figure shows the settings for switches 3
and 4 for the amount of memory on the system board.
0 '
2 3 '
5.7.~
128K
fDD~~DDDD
'\.
\
192K
rDD~~DDDD~
'\. \
256K
lDD~~DDDD\
'\.
\
Note: The system board must be fully populated,
256KB of memory, before a memory expansion
option can be installed.
4-8 Switch Settings