Apple II, Atari 800
The Illustrator was written entirely in 6502 Assembly language. The entire program as well as all the data had to reside in the limited 48k memory of an Apple II computer.
The Illustrator possessed some very advance features for its time. It had a point and click, hierarchical menu system. In addition to line and freehand drawing, objects could be moved, resized, and rotated. Objects could be grouped together, and pictures could be zoomed into. Drawing could be printed.
An Apple Graphics Tablet was the preferred means for drawing, in fact the Illustrator was developed in order to support the tablet. But the tablet's cost, $650, as well as the fact that Apple did not supply software for the tablet meant that it was not a success and Apple withdrew it from the marketplace. That it turn limited the success of the Illustrator.
Read the Manual
Graphics Processing System
Stoneware acquired the Illustrator from me and marketed it as the Graphics Processing System. They rewrote the manual, but the software remained as I had created it.