Service manual

3-1
CHAPTER
3
Power-On Self-Test
This chapter contains procedures to initiate the power-on self-test (POST)
diagnostics. Procedures are also included to support pre-POST preparation, POST
data interpretation, and bypassing POST diagnostics. The following is a list of the
POST diagnostic topics presented in this chapter.
■ Section 3.1 “POST Overview” on page 3-1
■ Section 3.2 “Pre-POST Preparation” on page 3-2
■ Section 3.3 “Initializing POST” on page 3-4
■ Section 3.4 “Maximum and Minimum Levels of POST” on page 3-6
■ Section 3.5 “POST Progress and Error Reporting” on page 3-12
■ Section 3.6 “Bypassing POST” on page 3-14
■ Section 3.7 “Additional Keyboard Control Commands” on page 3-14
■ Section 3.8 “System and Keyboard LEDs” on page 3-15
■ Section 3.9 “Initializing the Motherboard POST” on page 3-15
3.1 POST Overview
The POST is useful in determining if a portion of the system has failed and should
be replaced. POST detects approximately 85 percent of Ultra 2 series system faults
and is located in the system board OpenBoot PROM (OBP). The setting of the diag-