Post; System Board Hardware Tests - DEC DECpc 433 Service Manual

Troubleshooting
POST
Before your DECpc 433 Workstation can be used, all system components must
be initialized and tested, and the operating system loaded into memory. The
basic inpuVoutput system (BIOS) that is stored in ROM controls this sequence
of actions. A portion
of the BIOS contains
a Power-on Self Test (POST).
POST is responsible for initializing and testing system components each time
power is applied or when the system boots. The remainder of the BIOS loads
the operating system and specific applications.
POST consists of a set of tests used to check the condition of the system
circuitry and report system malfunctions. The organization of
POST
allows
testing to progress from the lowest level of hardware to the initialization of
external peripherals e.g., disk drives, keyboard, monitor, etc.
There are two types ot POST tests: system board hardware and peripheral
harU.ware.
System Board Hardware Tests
POST checks the system board hardware first. If any of these tests fail, a fatal
error condition exists and further testing and initialization is not possible.
You are notified that an error condition exists by the lighted fault LEDs on
the system board and/or intelligent graphics controller, an error message
displayed on the monitor screen, or beeps from the system speaker. Refer to
the I:sts of POST error messages and beep codes provided at the end of this
chapter. The following identifies the system hardware tests and their order of
execution:
• Programmable Interrupt Controller (PIC)
• 82340 chip set
• CPU
DECpc 433 Workstation Service Guide
2-3