12.3.2.1 describe the RISC architecture 
12.3.2.2 describe the CISC architecture 
12.3.2.3 compare RISC and CISC 

CISC vs RISC 

The two main types of computer processors are: 

• Complex Instruction Set Computing (CISC) 
• Reduced Instruction Set Computing (RISC) 

CISC	RISC
Complex Instruction Set	Reduced Instruction Set.
Non-fixed size of instruction, e.g. instructions have variable format.	Fixed-size of instruction
Uses complex instructions each of which may take multiple cycles.	Complex tasks can only be performed by combining several simple tasks so a task may take several machine cycles.
Many instructions and addressing modes are available. Can perform complex tasks faster.	A limited number of instructions are available. The instruction performs a simple task. Can perform simple tasks faster.
Small code sizes	Large code sizes
High cycles per second	Low cycles per second
Has a complicated and expensive processor design.	Simple processor design.
Has more components on the CPU than a RISC processor	Less components on CPU than in CISC processor
Use less RAM	Use more RAM
Produces more heat, requires heat sink/fan	Produces less heat
Used in PC	Used in tablets and mobile devices
Memory-to-memory	Register-to-register
Require more power	Require less power
Uses less registers than in RISC	Uses more registers than in CISC
Cannot use pipelining	Uses pipelining

Additionally

Questions:

1. Name features for CISC and RISC.
2. Explain the differences between CISC and RISC.
3. What type of processor is used for laptops? Why?

Exercises:

Ex. 1

Ex. 2 Complete the following text by using the words and phrases given below to fill in the gaps.

Ex. 3 Complete this task by selecting RISC and CISC processor characteristics.

Exam questions: