IBM Personal Computer XT Manual To Operations page 113

Test 700
1
Do you have an IBM Math Coprocessor
installed in your system?
NO - Continue with the next Test.
YES - Did the following appear and remain on
your screen for more than 10 seconds?
SYSTEM UNIT 600
YES - Have the system unit serviced.
NO - Go to the next step.
April 1984
Test 700-1