A complex system that works is invariably found to have evolved from a simple system that worked.
—John Gall (Ref [1])
The world of embedded systems is pretty much a farrago of everything, with each system having its own idiosyncrasies. In the old days, many systems would forgo microprocessors in favor of glue logic or application specific controllers to drive costs down. This makes it very hard to have a generalized discussion ...