2008-06-01 (updated 2013-12-10)
DoomEd as well as the DOS version of DOOM were developed on a several platforms running NeXTSTEP 3.3. NeXTSTEP's design didn't really care if these systems were 68k, x86, or PPC:
Quoted from John Romero:
In fact, with the superpower of NeXTSTEP, one of the earliest incarnations of DoomEd had Carmack in his office, me in my office, DoomEd running on both our computers and both of us editing one map together at the same time. I could see John moving entities around on my screen as I drew new walls. Shared memory spaces and distributed objects. Pure magic.