QED is a line-oriented computer text editor that was developed by Butler Lampson and L. Peter Deutsch for the Berkeley Timesharing System running on the SDS 940.
[2][3] QED (for "quick editor")[4] addressed teleprinter usage, but systems "for CRT displays [were] not considered, since many of their design considerations [were] quite different.
The Multics version was ported to the GE-600 system used at Bell Labs in the late 1960s under GECOS and later GCOS after Honeywell took over GE's computer business.
A version of QED named FRED (Friendly Editor) was written at the University of Waterloo for Honeywell systems[10] by Peter Fraser.
QED was also used as a character-oriented editor on the Norwegian-made Norsk Data systems, first Nord TSS, then Sintran III.