Chapter 1: Instructions

Question 1

Why do we use an assembly language?

Answer 1

This is because it is hard to remember all of the specific binary codes for different operations.

Question 2

What is a complex Instruction set (CISC)

Answer 2

Occurs when there is a large number of instructions, all of these instructions need to be retained in order to allow old programmes to still work.

Question 3

What is a Reduced Instruction set (RISC)

Answer 3

Normally faster hardware that has been adapted to use a small instruction set using a limited number of basic functions.

Question 4

Disadvantages of RISC?

Answer 4

The danger with RISC architectures is that as they evolve, they transform into a CISC architecture. For example, the ARM RISC architecture initially had 46 instructions. More recently the latest processor has more like several hundred.

Question 5

Disadvantages of CISC?

Answer 5

• The hardware required for lots of instructions (often consisting of variable numbers of bits) is harder to design and optimize for low power operation.
• Furthermore, some of these instructions took longer to carry out than others, making it more difficult to optimize the speed.