 Singer in 1984 using Altair Basic, and modified by John Zaitseff for Microsoft Basic under the CP/M-80 operating system in 1988.Completely rewritten versions for CP/M-80, CP/M-86, MS-DOS, Microsoft Windows 3.1 and Linux/Unix followed, with the latest release for Linux and Unix occurring in November 2019.All versions by John Zaitseff have been released or relicensed under the GNU General Public License v3.