I remember reading somewhere (maybe on Hacker News or Lobsters) that Motorola made a microprocessor some decades ago with two sets of registers. This means when handling an interrupt, it does not need to do the saving/loading. Does anybody know the name of the microprocessor?
Googling wasn't helpful: it just returns pages after pages of result about Motorola 6800(0), which doesn't seem to have two sets of registers.
Bonus points for explaining why this design didn't go popular. I mean, it sounds like a good idea.