CISC ALSO CAN BE IMPLEMENTED BY USING HARDWIRED CONTROL

In the above sense, micro programmed control is not always necessary to implement CISC machines. Hardwired control also can be used for implementing sophisticated CISC machines. The bases of this opinion are as follows:

1. The same field configuration (state assignment) can be used for both of these two types of control. This is clear because of the above identification.

2. We can use any large FSM, that has horizontal microcode like state assignment, since the delay for the FSM does not matter at all so long as it is less than or equal to the delay for the data-path that includes adders, shifters and so on, since the FSM works in parallel with the data-path.

3. The horizontal microcode like state assignment has become very easy to be implemented because of the spread of the hardware description language (HDL). In Verilog HDL, g`defineh statements enable us to get perfect net-list for any large FSMs in a very short time by using appropriate logic synthesizers. “Parameter” statements also can be used for the state assignment in Verilog HDL.

4. CISCs and RISCs are two major different types of ordinary SISD machines. Since hardwired control has been historically faster, both of these two types of machines are implemented by using hardwired control in our microcomputer design educational environment City-1.

5. In 1996, that was the first year of City-1, an example description named CISC-1 with an FSM that uses a horizontal microcode like state assignment was given to all of junior students of the Department of Computer Engineering, Faculty of Information Sciences, Hiroshima City University. They succeeded.