Although
the 360 series predated the availability of semiconducter ROM,the advantages
of microprogramming were compelling enough for IBM to make this move. Microprogramming
became a popular technique for implementing the control unit of CISC
processors. In recent years, microprogramming has become less used but remains a tool
available to computer designers. For example, as we have seen, on the Pentium 4, machine
instructions are converted into a RISC-like format most of which are executed
without the use of microprogramming. However, some of the instructions are executed
using microprogramming