PC-Write

PC-Write was a word processor originally released in 1983 by a company (now defunct) called Quicksoft. It was released on a shareware basis, with a paid version available.

The files were basically plain text, with optional special functions causing control characters to be inserted. However, the default filename suggested when you started the program was "WORK.DOC", suggesting .doc as the default file extension to be used, which could be confusing given MS-Word's more well-known use of this extension. You could create or edit files with any extension, including .txt, however.

If you stick to characters found in the ASCII character encoding, and don't use any special PC-Write features, the resulting files will be completely ASCII, using the standard PC-DOS carriage return + linefeed for line breaks. If you use accented characters (you could type them by typing a letter, then the backtick (`), then another character representing the diacritical mark such as an apostrophe or tilde), those will use the active MS-DOS code page. Other features (accessed within PC-Write through Alt key combinations) will cause various control characters to be inserted into the file, but the rest of the content will remain plain text. The control characters have meanings that are specific to PC-Write, not generally resembling their "official" meaning in the ASCII set; for instance, a variety of special commands are done as "dot commands" (on a line by themselves, with a dot followed by a special command) which are preceded by a control character that is entered as Alt-G in PC-Write but stored as Ctrl-K, which is officially the Vertical Tab character in ASCII.