HP 400 Series Servicing Manual page 109

Table 4-6 lists these messages. The address' 5 most significant hexadecimal digits are
FFFFF, so only the 3 least significant digits (LSD) are used in the table. When a range
of addresses is shown, each address in the range is six addresses apart.
When an "UNEXPECTED" failure message equates to an interrupt level, vectored
interrupt, or trap, the following situations normally exist:
Interrupt levels 1 through 7
Can happen at any time and are usually caused by an interface set
to the indicated interrupt level. If the error repeats, replace the CPU
board.
CPU traps Usually occur when the operating system is being used. A CPU
trap indicates something in the processor circuits didn't go right. If
the error repeats, replace the emulator or CPU board.
Other errors Several things on the CPU/emulator board in an interface or pro-
cessor circuit can cause these errors. If the error repeats, replace the
CPU or emulator board.
Fault Isolation 4-39