1.1.2 types of processor

• Set of all instructions written in machine code that can be recognised and executed by a given processing unit/CPU • CISC AND RISC

• Reduced Instruction Set Computing • Instruction set made up of a small number of simple, fixed-length instructions/commands • 1 instruction executed per clock cycle (designed to process simple instructions quickly)

• ARM processors

• tablets, smartphones, and embedded systems, where it is not necessary to carry out complex instructions.

• simpler instruction design (all instructions are uniform in terms of execution time) makes pipelining easier to implement –> increases performance of RISC. • simpler instructions mean programs run faster • require less circuitry (fewer transistors) –> cheaper to design and produce, give off less heat, consume less power and leaves more room for general purpose registers and cache -lower energy requirements

• several instructions needed therefore low-level programs for RISC processors are longer and take up more memory. • Uses a lot RAM to store assembly instructions (more lines of code required). Can cause system bottlenecks if RAM is limited • Emphasises software over hardware: high-level compilers that simplify and translate programmers code do more work • larger code sizes • fewer addressing modes available

• Complex Instruction Set Computing • large number of complex instructions of variable length each taking multiple cycles to carry out

• most desktops computer and laptops • Intel (x86) and AMD

• simpler software (compiler does less work as emphasis is on hardware) • larger instruction set = work better with more intensive tasks (executes complex instructions and carry out a number of low-level operations as part of a single instruction) • more specialised instructions means low-level programs for CISC processors take up less space in memory and are easier to translate to machine code. • small code sizes, multiple clock cycles to execute -makes more efficient use of RAM (CISC requires less to store instructions) -multiple addressing modes available

• More circuitry (transistors) needed to execute complex tasks as it aims to complete in as few lines of assembly as possible. (expensive) -greater energy consumption, gives off more heat • instructions can take multiple machine/clock cycles to execute —> makes pipelining difficult therefore CISC processing used for specialist computer systems

• any additional processor used for a specialised task

• tech advanced —> demand increase on single CPU • improve overall speed of computer by executing concurrently with main CPU, aided by a highly bespoke set of electronics

• central processing unit is a more general purpose processor in contrast to graphics processing unit which is highly specialised - designed specifically for graphics • CPU excels at performing complex operations on small data sets but GPU excels at performing simple operations on larger data sets

• Parallel Processing • improves performance of video/graphic-intensive applications

• SIMD • because mass calculation associated to graphics processing take full advantage of parallel processing • able to perform an instruction on multiple data locations at the same time

• Simple Instruction Multiple Data

• parallel processing when a processor carries out single instruction on multiple data items at the same time

• weather modelling • data mining • machine learning • linear algebra • statistical analysis • cryptocurrency to mine bitcoins • graphics rendering, pixel shading

• facility for producing some form of basic visual output by mapping values in memory to pixels on a screen

• this design frees up main processor to handle other tasks.

• own set of RAM and processor (GPU)

• machine learning applications. • GPUs with 1000’s of cores = optimised to parallel process calculations, required for machine learning algorithms (usually good for one task)

• training a neural network

• as each core performs a small part of the whole operation.