XTree is a file manager program originally designed for use under DOS. It was published by Underwear Systems, later Executive Systems, Inc. (ESI) and first released on 1 April 1985, and became highly popular. The program uses a character-mode interface, which has many elements typically associated with a graphical user interface.
ZTreeWin 2.1
DOS is a family of disk-based operating systems for IBM PC compatible computers. The DOS family primarily consists of IBM PC DOS and a rebranded version, Microsoft's MS-DOS, both of which were introduced in 1981. Later compatible systems from other manufacturers include DR-DOS (1988), ROM-DOS (1989), PTS-DOS (1993), and FreeDOS (1998). MS-DOS dominated the IBM PC compatible market between 1981 and 1995.
The IBM Personal Computer (IBM 5150 PC)