IBM Personal Computer XT Manual To Operations page 49

Power-On Self Test (POST)
1
Turn the Brightness and Contrast controls fully
clockwise. When the first screen presentation
appears, adjust the controls for eye comfort.
2
Set the Power switches on all attached devices to
On.
3
If the expansion unit is attached, set its Power
switch to On.
4
Set the system unit's Power switch to On.
April 1984
Start 30-1