Modern Airliners: Guided by the 386 chip?

I was somewhat surprised today to read, in a Wikipedia article discussing autopilot systems, that the autopilot systems used by today's aircraft are powered by the humble 386 chip. Somehow, I foolishly thought that the airlines would have upgraded to at least Pentium I systems by now, but no, the old 386 chip is so cheap and so stable that it's the clear choice for autopilot systems (which use 5 of them).