I'm not having trouble parsing a file name.

It's the command-line interpreter that feeds the file name to the UPLOAD.EXE code. Command-line code under Windows is all old throwbacks to DOS, which didn't have network UNCs. You can't send a network UNC path to an old command-line app, at least not without a lot of special-case code.

Ideally, I would completely remove the UPLOAD.EXE command line applet and have the logo editor grab the COM port directly and do all of the handshaking work itself. If I did that, then there wouldn't be an issue.

However, that's a lot of work. It was easier just to use the existing DOWNLOAD.C code from Hugo and recompile it for Win32 with an extra parameter. That's what made the difference between Logo Editor becoming a reality and being just a dream. If I'd had to rewrite all the serial communications protocol stuff, I wouldn't have ever finished it. Maybe not even started it.

So, as a result, my code has to mash the path down to a short-file-name that's acceptible to pass on the command line to DOWNLOAD.C. And if it's a UNC, it can't mash it into a short-file-name (by definition).

Hence the error when trying to work with UNCs as fed to UPLOAD.EXE.