Texas Instruments 990 Operation Manual page 59

~~-------------------
~
945255-9701
A checksum error which represents an inaccurate reading of the object code should not be
ignored. The record should be reread at least once in the attempt to read it correctly. However,
a checksum error may be the result of altering the contents of an object record without
removing the checksum field. This type of checksum error may be ignored.
The third message is:
M Multiply-Defined Symbol
PX9LAL prints an "M" for each multiply-defined external definition encountered when pro-
cessing a module. When a full memory map is being printed, the "M" is printed on the external
definition line. When a partial memory map is being printed, an "M" for each multiply-defmed
symbol in the module follows the module name and load point.
When the second definition is required in the program instead of the first, change the load
sequence to load the program module that contains the desired definition first and reload. When
both definitions are required in the program, change one of the symbols and reload. This may
also require changing corresponding references to avoid other errors. When the symbol of the
defmition contains the first six characters of the IDT character string of a previously loaded
program module, change the symbol and corresponding references or the IDT character string
and its reference, and reload. When the definition is not required in the program, ignore the
message.
The fourth message is:
UNDEFINED Undefmed Symbols
When all modules have been processed, and the user enters "E" to the "LOAD/END" option,
PX9LAL scans the symbol table to find any symbols that are not defined. If any undefined
symbols are found, this message followed by a list of undefmed symbols is printed.
An intentionally undefmed external reference (dummy reference) that is included in one of the
modules of a program pennits a type of load-time patching. If external references have been
inadvertently omitted, a program module may be generated that uses the deliberately undefmed
reference as the IDT character string, and consists of absolute external definitions to satisfy
program requirements. PX9LAL loads this module, and the program is ready for execution. If
the deliberately undefmed reference is the only undefined reference, the program may be
executed properly with the reference remaining undefmed. This technique is intended for use
during program development.
3.4.6.4 Examples of Load Map Printouts. The following five examples show load map printouts
of load operations with and without linking.
3-21
Digital Systems Division