Silicon Graphics Zx10, User Manual

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Chapter 5
5. Messages
This chapter describes POST tasks and beep codes, and system board error messages.
POST Tasks and Beep Codes
When you turn on power to or restart the system, the system’s basic input/output
system (BIOS) runs a number of tasks. These power-on self test (POST) tasks test and
initialize the system hardware and then boot the operating system from the system’s
primary hard disk drive.
At the beginning of each POST task, the BIOS sends a test-point error code to
input/output (I/O) port 80h. Programmers and technicians use this code during
troubleshooting to establish at what point the system failed and what POST task was
being run. If the BIOS detects a terminal error condition, it issues a terminal-error beep
code, attempts to display the error code on screen, and stops POST. If the system hangs
before the BIOS can process the error, the value displayed at I/O port 80h is the last POST
task run. In this case, the error code does not display on screen.
The following is a list of test point codes written to I/O port 80h at the start of each task.
The tasks are arranged by test point number in the BIOS code. The beep codes are listed
for terminal errors, and are short groups of beeps that represent the terminal error code
in four two-bit groups.
Table 5-1 Test Point Codes
Code Beeps POST Routine Description
01h BIOS has started execution
02h Verify Real Mode
03h Disable Non-Maskable Interrupt (NMI)
04h Get CPU type