If you have viewed a Web page containing strange characters you did not understand, you may have seen Unicode characters. Unicode consists of a character set that covers most languages in the world.

When MS-DOS 5.0 was launched in 1991, one of its major innovations was the MS-DOS Editor, a classic text editor that quickly became popular with users. These days, it’s old news—yet fondly remembered.

Last month, Microsoft released a modern remake of its classic MS-DOS Editor, bringing back a piece of computing history that first appeared in MS-DOS 5.0 back in 1991. The new open source tool, built ...