This document discusses different types of parallel processing architectures: - SISD refers to traditional single processor systems that execute a single instruction stream on one data stream. - SIMD systems have multiple processing units that execute the same instruction on different data elements simultaneously. GPUs commonly use this architecture. - MIMD systems have multiple independent processors that can each execute different instruction streams on different data streams, like modern multi-core CPUs.

1. Parallel Processing
Branch: Computer Science Engineering
Subject: Computer Organisation

2. • It uses two basic concepts
• Parallelism in instruction stream
• Parallelism in data stream
• A CPU has n Program Counter so there are n
Instruction streams
• A data stream can be used as sequence of data
• It has 4 possible combinations

3. • SISD
• SIMD
• MISD
• MIMD

4. Features
• One Job at one time
• SISD corresponds to traditional mono processors
• Single data stream handled by single instruction
• A. Uniprocessor system which generates single stream of
instruction from program

5. SISD Representation

6. SISD Processor
CRAY T3e : SISD based architecture
Used in embedded systems

7. Features
•Single CU multiple Processing unit
•All processing units are synchronised
•Instructions on different sets on data
•CU fetches instruction from memory and distributes
into multiple Processing units

9. SIMD processer
GPU generally use this architecture
ILLIAC IV first SIMD based processer

10. Features
•Many functions are executing on same data
• Can be manufactured but not commercially released
•Used by systolic arrays

11. MISD Representation

12. MISD Processor
Systolic arrays
Multiple processors are connected in 1D-2D arrays

13. Features
•It is true Multiprocessor
•In contrast to SIMD, MIMD is general purpose machine
•When all cores/processer run one program it's called
SPMD(single program multi data)
•Usually every processor has own data to execute

14. MIMD Representation

15. MIMD Processor
Any modern day CPU is MIMD architecture based
Multiple cores acts as multiple instruction which fetches multiple data streams

16. THANK YOU
Hope you gained some knowledge :)