HP 3000 III Series Manual page 132

Machine Instructions and Stack Operations
(3) In PCAL and interrupt handler when setting up a new
segment, the STT number in the external program label
points to an external program label in the new segment.
(4) In SCAL, (PL-N) is an external label.
c. STT #18; CSTV - Code Segment Table Violation. An attempt is
made to transfer to Segment 0 or 192, or a segment number is
greater than the CST length.
d. STT #19; DSTV - Data Segment Table Violation. The data seg-
ment number referenced by MFDS, MTDS, or MDS is greater than
the DST length or is
o.
e. STT #20; STUN - Stack Underflow. The process being executed
or being transferred to is non-privileged and SM is less than
DB.
f. STT #21; MODE - Privileged Mode Violation. The code segment
being executed is non-privileged (bit 0 of the Status Reg-
ister is 0) and an attempt is made to execute a privileged
instruction. This violation also occurs in EXIT if an at-
tempt is made to exit from user to privileged mode or, if
exiting from user mode, the External Interrupts bit in the
Status Register has been al tered.
g. STT #24; STOV - Stack Overflow. SM is greater than Z or may
become greater as a result of the current instruction.
h. STT #25; ARITH - Arithmetic. All User Traps will be executed
in the segment #1 routine pointed to by STT #25. The error
conditions and their parameters are as follows:
Inte rrupt Type
Integer Overflow
Floating Point Overflow
Floating Point Underflow
Integer Divide-by-Zero
Floa t ing Po in t Di v ide- by-Ze ro
Octal
Parame ters
000001
000002
000003
000004
000005
i. STT #31; ABS CST - Absent Code Segment. The absence bit in
the CST entry for the referenced segment is set. The inter-
rupt handler and PCAL stack a (second) marker; others in-
cluding EXIT, IXIT, etc., do not.
j.
STT #32; TRACE - Code Segment Trace. Code segment is being
tr aced.
k. STT #33; UNCALL - Uncallable STT Entry. The uncallable bit
in a local label or, if the STT number is 0, in (PL) is set.
This trap does not stack a (second) marker.
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