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Service Manual PRELIMINARY
4.5.2
Double Error Halt
A double error halt occurs under the following conditions:
•
A machine check occurs.
•
PAL completes its tasks and returns control of the system to the operating
system.
•
A second machine check occurs before the operating system completes its tasks.
The machine returns to the console and displays the following message:
halt code = 6
double error halt
PC = 20000004
Your system has halted due to an irrecoverable
error. Record the error halt code and PC and
contact your Digital Services representative. In
addition, type INFO 5 and INFO 8 at the console and
record the results.
The info 5 command (Example 4–2) causes the SRM console to read the PAL-built
logout area that contains all the data used by the operating system to create the error
entry.
The info 8 command (Example 4–3) causes the SRM console to read the IOD 0 and
IOD 1 registers.
4.5.3
Machine Checks While in PAL
If a machine check occurs while the system is running PALcode, PALcode returns
to the SRM console, not to the operating system. The SRM console writes the
following message:
halt code = 7
machine check while in PAL mode
PC = 20000004
Your system has halted due to an irrecoverable
error. Record the error halt code and PC and
contact your Digital Services representative. In
addition, type INFO 3 and INFO 8 at the console and
record the results.
The info 3 command (Example 4–1) causes the SRM console to read the “impure
area,” which contains the state of the CPU before it entered PAL.
Example 4–1 INFO 3 Command
P00>>> info 3
