1.1.2 Types of Processors

What are the types of processor?

#Reduced instructionset computer (RISC)

Complex instruction set computer(CISC)

What are the characteristics of RISC processors?

• Uses simple, fixed-time instructions (1 per clock cycle).

• Needs more instructions for tasks → longer programs, more memory.

• Easier pipelining → better performance.

• Less circuitry → cheaper, cooler, lower power.

• Ideal for phones, tablets, battery devices, and supercomputers (fast parallel processing).

What are characteristics of CISC processors?

#Uses complex instructions (multiple operations in one, e.g., load + add + store).

• Shorter programs, less memory, easier to code.

• Harder pipelining → traditionally for specialist systems.

• More complex, hotter, higher power.

What doe modern CPUs use?

#Combine RISC + CISC for best of both.

• More complex, hotter → need good cooling → used in desktops, laptops.

What are the main features of CISC?

#

Instruction set is made up of a large number of complex, variable-length instructions

Instructions can take several clock cycles to be executed

Compound addressing modes

Emphasises hardware over software: the ISA does as much as possible using processor hardware circuitry

Makes efficient use of RAM

What are the main features of RISC?

#

Instruction set is made up of a small number of simple, fixed-length instructions

One instruction is executed per clock cycle

Limited addressing modes

Emphasises software over hardware: high-level compilers take on most of the burden of translating many software steps from the programmer

Uses a lot of RAM, which can cause system bottlenecks

What are GPUs designed to do?

#GPUs are designed for parallel processing and are used in a wide range of applications, including graphics and video rendering.