...memory.
I pulled this off with one of the dirtiest technological tricks in my inky-black hacking career. There was no compiler for the Macintosh which generated 32 bit code, permitted data segments larger than 32K, or compiled in-line floating point instructions: all prerequisites for AutoCAD. But, I noted, at the very same time we were shipping AutoCAD on the Sun 3, which used the very same Motorola 68020 microprocessor as the Macintosh II. So, I simply compiled all of AutoCAD except for the display, keyboard, mouse, and file I/O drivers on the Sun, linking them into one huge relocatable file which I called ``The Titanic''. Then, using LightSpeed (later Think) C, I wrote a small conventional Macintosh application which obtained a large chunk of memory, loaded the Titanic into this block of memory, dynamically relocating it and linking external references in it to ``stubroutines'' defined in the Macintosh program, and then launching it. The Macintosh program, ``Tugboat,'' thus nudged the Titanic into place on the Macintosh. Believe it or not, this all worked (though debugging it with a joke-debugger called TMON which couldn't disassemble the 68020 instructions generated by the Sun compiler is a memory still powerful enough to make me grind my teeth), and this is how we finally (after a lot more work by many other people) shipped Release 10 for the Macintosh.