3.2 Power-On Self-Test (POST)
The POST is initiated automatically each time the system power is turned
on.
The POST is a series of system checks and initializations that verify the
correct operation of the system unit. The POST tests only those areas
that allow the system to be operational enough to run advanced
diagnostics. The POST can detect two types of errors: critical and
noncritical.
Critical errors prevent the system from operating or can cause incorrect
results that are apparent to the user. Examples of critical errors
include microprocessor or interrupt-controller errors. If the POST
detects a critical error, the microprocessor attempts to display the error
and all testing stops.
Noncritical errors cause incorrect results that might not be apparent to
the user. An example of a noncritical error would be a serial
communications failure. If the POST detects a noncritical error, all
testing stops and the microprocessor attempts to display the error.
Pressing F1 allows testing to continue.
When the Advanced Diagnostics Diskette is in drive A (Model 35 SX) or in
the server (Model 35 LS) and it is ready to be loaded, and a noncritical
error is detected, the system displays the POST error message along with a
message generated from the Advanced Diagnostics Diskette. The Advanced
Diagnostics Diskette message instructs the user to take a specific action
to correct the error.
After a successful POST, one short beep occurs. Control is then given to
a BIOS routine called the system bootstrap loader. The bootstrap loader
attempts to load an operating system or a program from either a diskette,
the hard disk drive, or the server of the network. If no operating system
or program is found, the IBM BASIC screen appears.
IBM PS/2 Model 35 SX, 35 LS, 35 SLC HMR
Power-On Self-Test (POST)
¦ Copyright IBM Corp. 1991, 1992
3.2 - 1
