In his own words:
"In 1984, I was hired as the 4th engineer at subLOGIC Bruce Artwick, Dave Denhart, Charles Guy and myself were the
entire engineering department there. I was hired specifically to develop scenery for all the Flight
Simulators. At the time, there were three 6502 versions of FSII. There was one for the Apple II,
one for the Commodore 64 and one for the Atari 800.
When the the Atari ST and Amiga were introduced (which ran the Motorolla 68000 processor), new versions were released for those machines, for the Tandy and for the MacIntosh through Microsoft. The versions of FSII for the 6502 processor DID have solid filled graphics not just wireframe.
There was only 6k memory allotted for scenery so a sophisticated system of loading parts of the scenery was devised. The whole FS world was big enough to properly place and scale landmarks and airports relative to each other. That was accomplished by a brilliant hybrid coordinate system that Bruce Artwick developed. Also, the simulation was sophisticated enough to support instrument navigation.