Control versus Datapath
▪ Processor designs split between datapath, where numbers are stored and
arithmetic operations computed, and control, which sequences operations on
datapath
▪ Biggest challenge for computer designers was getting control correct
▪ Maurice Wilkes invented the
idea of microprogramming to
design the control unit of a
processor*
▪ Logic expensive vs. ROM or RAM
▪ ROM cheaper than RAM
▪ ROM much faster than RAM
4
* "Micro-programming and the design of the control circuits in an electronic digital computer,"
M. Wilkes, and J. Stringer. Mathematical Proc. of the Cambridge Philosophical Society, Vol. 49, 1953.
