Types of processor

Types of processor

1. Von Neumann Machine

   • Same data bus transfers data AND instructions
   • Single Address bus transfers addresses for data AND instrucitons
   • Same word length used for all memory

2. Harvard Architecture

   • Separates memories for instructions and data
   • Used extensively with Digital Signal Processing
   • Different memories can have different characteristics
     • In embedded systems, instructions may be held in ROM and data in RW memory
   • Some systems have more instruction memory than data memory - larger word size for instructions
   • Instruction address bus may be wider than data bus
   • Faster than von neumann as instructions & data can be fetched in parallel

3. Contemporary processor architectures

   • Incorporate aspects of bon Neumann and Harvard
   • There is one memory for data and instructions
   • Cache is split into one for instructions and one for data

4. Reduced Instruction Set Computers

   • Simpler instructions - simple decoding
   • Instructions less than one word size
   • Instructions take one clock cycle to be executed
   • More general purpose registers
   • Simple addressing modes
   • Fewer data types
   • Pipeline can be achieved

5. Complex Instruction Set Computers

   • Complex instructions, complex decoding
   • Instructions larger than one word size
   • Instruction may take longer than one clock cycle
   • Less general purpose registers
   • Complex addressing modes
   • More Data types

6. Co-Processor

   • Handling floating point numbers requires wide registers
   • Co-Processor handles these numbers instead of CPU
   • Handles them very quickly
   • When a floating point calculation needs to be done, CPU hands task over to co-processor
   • More expensive and takes up power and space

7. Multi-core Processor

   • Refers to any CPU with more than one core
   • Some commercial processors have up to 64 cores
   • Multiple cores should process data faster (not always the case)
   • Some software not designed to take advantage of multiple cores

8. Parallel System

   • Relies on software taking advantage of multiple cores
   • Divides instructions between multiple processor cores
   • Ways to parallel process
     • Assign each processor to parts of Fetch-Decode-Execute cycle
     • Split process in separate task and assign to each processor

9. GPU - Graphics Processing Unit

   • Primary purpose to process images
   • Have a parallel architecture with thousands of small efficient cores
   • Either stand alone graphics cards or integrated on the motherboard
   • Recently been used for AI applications, oil exploration and financial transactions