I still have a program I use rarely where I have to set my PC clock back before 2000 to run.
It was a compiler basic program where I lost the source code so I couldn’t fix it. Just got the .exe
For coders, the program created a log file with a date in the filename and used the 1985 dos method of processing dates. So in 1999 the ‘9’ incremented to the next ascii character, which is I think a quote of something that. It is illegal in a filename.
” So in 1999 the ‘9’ incremented to the next ascii character, which is I think a quote of something that. It is illegal in a filename.”
That is not how dates were processed.
Rereading your post I see that you may have been the developer of your program?
If so, what you did was mighty strange coding!
Please, use the term "programmer". Coder is used by those who have no clue.