1.1.2.1 RISC and CISC processors

Question 1

What is a RISC?

Answer 1

• Reduced Instruction Set Computer
• A simpler processor design that can only execute a single simple instruction each clock cycle.
• This uses more RAM but allows pipelining

Question 2

What are features of a RISC.

Answer 2

• The compiler has to do more work to translate high level code into machine code.
• More RAM is required to store the code.
• Pipelining is possible since each instruction takes one clock cycle.

Question 3

What is a CISC?

Answer 3

• Complex Instruction Set Computer
• In these processors there is a large instruction set.
• These instructions are built into the
  hardware .
• The aim is to try and accomplish tasks in as few lines of assembly code as possible.
• They have a more complicated and expensive processor design that can execute a series of tasks in a single complex instruction built into the hardware.
• The variety of instructions means less RAM is used, but pipelining is not possible.
• Early on these processors were used as the standard, however with time they got replaced by RISC design.
• Now they are used more in micro-controllers and embedded systems.

Question 4

What are features of a CISC.

Answer 4

• The compiler has less work to translate
  high level code into machine code.
• Less RAM is required since code is
  shorter.
• Many specialized instructions are made,
  even though only a few of them are used.