This paper gives a description of a simplified disk-editor which is to be manipulated through a character display unit. This disk-editor is designed for the editing of files on the disk attached to the computer system MELCOM 9100/30F which is installed in our college. The editing operation is intended to be performed on the conversational basis. The editor is written in ASSEMBLY language and FORTRAN language complementarily, and it is operated in two different modes, READY mode and EDIT mode. Each mode includes ten commands. Some examples of usage of the editor using these commands are also presented.