IBM 5155 Manual To Operations page 53

Power-On Self Test (POST)
1
Turn the Brightness and Contrast controls fully
clockwise. After the first screen is displayed
adjust the controls for eye comfort.
D
2
Set the Power switches on all external 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.
January 1984
Start
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