Technical data

Information about the error
ISTACK ID Meaning
ACCU 1...4
Contents of the calculation registers at the time of
interruption:
in the event of certain errors, the system program
writes error identifiers into
ACCUs 1 and 2 when the interruption occurs.
These identifiers define the cause of the
interruption more exactly
Table 5-6 continued:
BRACKETS
Number of bracketed levels:
"KEx abc"
x = 1 to 7 levels
a = OR (OR see condition code bits)
b = RLO (result of logic operation, see
condition code bits)
c = 1: A(
c = 0: O(
Condition code see Section 3.5
Cause of interrupt The following abbreviations (ISTACK IDs) represent the most
important causes of interruptions.
The only causes of interruptions that are marked are those that have
occurred in the currently displayed program processing level (see
LEVEL).
The causes of interruptions represent the contents of the interrupt
condition code group word (ICMK, 16 bits, see Section 8.3.5). Some
of the entries here are identical to those in the control bits.
Cause of interrupt
ISTACK
ID
Meaning (called error OB)
NAU
Power supply failure in central controller
PEU
Peripherals not ready = power failure in expansion unit
Table 5-7 ISTACK IDs cause of interrupt
Control Bits and Interrupt Stack
CPU 928B Programming Guide
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