In 1987, Intel improved their process from 1.5 µm to 1 µm, making a much smaller 386 die. It's not a simple, mechanical process: they rotated the instruction decode unit and changed standard-cell generation, but left the datapath mostly the same. Left: 1.5 µm, right: 1 µm. 4/9
The 386 die cost dropped until the ceramic package cost as much as the die. Intel introduced the stripped-down 386 SX with a 16-bit bus that could go in a cheap plastic package, replacing the 286 in the low-end market. The original 386 was renamed the DX. Photo: 1.5, 1 µm SX. 5/9