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+15 votes
1.6k views

The main difference(s) between a CISC and a RISC processor is/are that a RISC processor typically

  1. has fewer instructions
  2. has fewer addressing modes
  3. has more registers
  4. is easier to implement using hard-wired logic
asked in CO & Architecture by Veteran (59.7k points)
retagged by | 1.6k views

2 Answers

+14 votes
+1
Option a.  isn't always correct and RISC instruction set can have more instructions than CISC. For reference, one can read Wikipedia page on RISC which states that in many cases, RISC set will have more instructions than CISC. "Reduced" in RISC means less work and not less instructions.

FROM Wikipedia-
A common misunderstanding of the phrase "reduced instruction set computer" is the mistaken idea that instructions are simply eliminated, resulting in a smaller set of instructions.[20] In fact, over the years, RISC instruction sets have grown in size, and today many of them have a larger set of instructions than many CISC CPUs. Some RISC processors such as the PowerPC have instruction sets as large as the CISC.
0

D) cannot be true

because RISC emphasis on software

https://cs.stanford.edu/people/eroberts/courses/soco/projects/risc/risccisc/

0 votes
Naswer is B and C

It support fixed length instruction. Not fewer instruction

It has less no addressing modes-- true

It has more register -- true

It is easier to implement using hardwired control logic -- False . Hradwired control logic is implemented inSOP form . Even a slight modification would require the whole circuit to redesign . It is faster but not easier
answered by Loyal (10k points)
0
@arjun sir : This wrong answer again selected !
+1
Any reference to show that RISC does not have fewer instructions? Fixed size indirectly reduces the no. of possible instructions.

"It is easier to implement using hardwired logic" - The comparison is with CISC instructions only- that is relative easiness.
0
Wikipedia page for RISC states and I quote

"A common misunderstanding of the phrase "reduced instruction set computer" is the mistaken idea that instructions are simply eliminated, resulting in a smaller set of instructions.[20] In fact, over the years, RISC instruction sets have grown in size, and today many of them have a larger set of instructions than many CISC CPUs.[21][22] Some RISC processors such as the PowerPC have instruction sets as large as the CISC IBM System/370, for example"

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