IBM 5280 User's Setup Manual page 128

48. Make sure all 1 and 20 diskette drives have been checked.
If your system has both 1 and 20 diskette drives, system checkout procedures
must be completed for each diskette drive.
Read the progress check block and continue to the next step.
PROGRESS CHECK
1. You should have keyed a 2 and a Z at each keyboard on your system.
2. You should have keyed the characters ABC ... XYZ and 012 ... 789 at each
keyboard on your system.
3. You should have moved the verification diskette into and out of every
diskette drive, and moved the blank 20 diskette into and out of every 20
diskette drive on your
system~
User's Setup Procedures 121