The i386 had 275,000 transistors. The Core M has 1.3B on 82 mm^2 in the 14 nm Broadwell process. If all else were equal (which it isn't), the could make an i386 on 82 x 275,000/1.3E9 = 0.0173 mm^2 = a square 0.132 mm on a side.

The Michigan Micro Mote is huge compared to that, but it is more than just a CPU.

At $2/mm^2 (ballpark price boxed CPU price), the modern i386 would cost about $0.03.

Neat stuff.

Cheers,
Scott.