I think mechanical timers are (thankfully) pretty much a thing of the past, even in low-end models. Seems like practically every problem I ever had with an appliance was due to the timing motor dying. And microcontrollers surely are cheaper these days.

Seriously? I have another dishwasher that has controls for "wash top rack only", "bottom rack only", reduce water jet force to protect delicate crystal, delayed start (to run when electricity is cheaper), and other stuff I forget. Not essential, but useful at times.

When I was in engineering school we got a SDS minicomputer. At one point we wanted to buy some extra I/O ports. So after paying the appropriate sum (I want to say it was around $5K), we were given instructions on how to move a jumper wire.

There's a somewhat famous example of creating a whole product line out of one design here: http://steveblank.com/2009/04/... SuperMac once offered 9 different Mac graphics boards priced from $700 to $4,000. The only difference between them was hardware wait states added to slow down the cheaper models. It's a very entertaining read, from my old friend Steve Blank.

Well, maybe so. But I once worked on some security access control equipment based on 8-bit Motorola MCUs. They all used the same firmware image, but there was a "feature PROM" installed that told the chip which optional features the customer had paid for. The control panel for my low-end dishwasher looks just like the higher-priced models, but with some of the buttons missing. I'd almost bet that there are pads on the PC board ready to accept switches to select the extra cycles. And it shouldn't take any extra hardware to implement something like a "Rinse Hold" cycle.