The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
SYS1939
SYS1939Explanation
A program ran a numeric coprocessor instruction that tried to read or write
to storage that is past the end of a storage segment.
Action
Correct the program and retry the command.