The sad thing is Microsoft never wanted the backslash. It's all IBM's fault.<p>DOS 1.0 had no subdirectories. There was no slash: you didn't type A:\FOO.TXT, you typed A:FOO.TXT, and the prompt wasn't A:\>, but rather A>. Incidentally, this still works today, and sometimes DOS boots with a A> prompt.<p>In DOS 2.0, Microsoft decided to add UNIX-style directories, with . and .. for navigation, / as the separator, cd to change directory and so on. But there was a problem.<p>DOS 1.0 had used / for flags (e.g. DIR /W). Microsoft's solution to this was to switch to - for flags, but IBM didn't like this change. So Microsoft compromised on using \ as the directory separator and kept / in use for flags.<p>However, Microsoft clearly didn't like having to make this change. How do we know this? Well, DOS nonetheless also supported / for directories (and thus its successors, including Windows NT do), and, at least for a little while, contained a setting which let you use - as the flag character.