I'm looking for a hat I can wear (e.g. in car) here with the Arizona sun and I'm finding stories instead.
Like this one, the backslash in the prompt is missing and it's likely that it was due to whatever software was used was swallowing up the character—perhaps when sanitizing strings.
The default system prompt in DOS was just "C>" (letter of current drive plus a ">" character, though basically everyone changed it to include the current directory, so it would have been "C:\>" after boot.
(The reason why it was defaulting to just the drive letter is that early versions of MS-DOS didn't have support for directories.)