Chapter 2.2 Power-On Self-Test - Compaq Prolinea Family Maintenance & Serice Manual

4. Replace the unit cover and perform the desired troubleshooting.

Chapter 2.2 Power-On Self-Test

Power-on Self-Test (POST) is a series of diagnostic tests that runs
automatically when the system is turned on. POST checks the following
assemblies to ensure that the computer system is functioning properly:
o Keyboard
o Power supply
o System board
o System memory
o Memory modules
o Controllers
o Graphics system
o Diskette drives