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CHAPTER
71
ERROR
MESSAGES
Error
Detection
and
Reporting
The assemblers detect and report three classes
of
errors: source-file errors (including
control line errors), run-time errors, and assembler control syntax errors.
Source-file
errors
are indicated in the assembly listing
by
single-letter codes listed in
column 1
of
the erroneous source statement.
If
multiple errors occur in the same
statement, only the first error is reported. Each error
is
followed by a pointer
to
the
previous erroneous line to ease finding errors. A summary
of
source-file errors
is
sent to the console and list devices.
Run-time
errors
cause the assembly to terminate abnormally. An error message
of
the form:
error type
ERROR
is
sent to the console and list device (if listing
is
in progress) and control returns
to
ISIS-II.
Assembler control
errors
in the assembler command are reported on the console
device with the message:
COMMAND
ERROR
ISIS-II errors are shown as numerical codes. These are listed at the end of this
chapter and explained in more detail in the
ISIS-II
System
User's
Guide.
Error
Codes
Source-File
Errors
Code Source
B
Balance error. Parentheses
or
quote marks are unbalanced.
C Control line
error.
An
illegal control
has
been
specified
in
a control line or a
primary
control appears
in
Illegal context.
The
erroneous control
and
following
controls
on
the
same
line are ignored.
E Expression error.
Ao
expression
has
been
constructed erroneously; usually a
missing operator or
delimiter. Also caused
by
adjacent operands with
no
separating operator.
Illegal character. A statement contains
an
invalid
ASCII
character, or a
specified number is
illegal in the context of the number
base
in which it oc-
curs. Also issued if a carriage return character is not followed
by
a line-feed
character.
L Location counter error.
The
symbol being defined
has
been
illegally forward
referenced.
The
definition is
made
in
all cases except
macro
definitions. This
condition
can
be
corrected by moving the definition to precede all references.
7-1