Types of Processor Flashcards
What is the stored program concept?
- A program must be loaded into main memory to be executed by the processor.
- Instructions are fetched one at a time, decoded and executed sequentially by the processor.
- The sequence of instructions can only be changed by a conditional or unconditional jump instructions.
How are the data and programs stored in the von nuemann concept?
Instructions and data are stored in a common main memory, and transferred using a single shared bus.
How does the harvard architecture differ to the von neumann architecture?
- Separation of data and instruction into separate memories using different buses
- Program instructions and data are no longer competing for the same bus.
What are some comparisons between the vonn neumann and harvard architectures?
Von Neumann:
• Data and instructions share the same memory, both use the same word length
• One bus for data and instructions s a bottle neck,.
• Programs are optimised in size
• One bus is used to transfer data and instructions
Harvard:
• Instructions and data are held in separate memories
• Parallel data and instruction bus may be used, parallel data access.
• Programs tend to be large
What are some features of contemporary processor architectures?
Computers that incorporate aspects of both architectures:
• There is one main memory for holding both data and instructions
• Cache memory is divided into an instruction cache and a data cache, so data and instructions are retrieved using Harvard architecture. ( Harvard is used as the CPU accesses the cache ).
What is CISC?
Complex Instruction Set Computers.
How does CISC work?
• A large instruction set is used to complete tasks in as few lines of assembly language as possible
What is an advantage of CISC architecture?
- Compiler has very little work to do to translate a high level language statement into machine code.
- Code is short, very little RAM is required
Where are the CISC instructions present?
They are built into the machine’s hardware.
What is RISC?
Reduced Instruction Set Computers.
What does RISC achieve?
- minimum number of very simple instructions.
* Each taking one clock cycle, are used to accomplish all the required operations in multiple general purpose registers.
What are some advantages of CISC vs RISC?
- Quicker to code programs
- Compiler has very little work to do to translate a high level statement into machine code
- Because the code required is relatively short, very little RAM is required to store the instructions.
What are some advantages of RISC against CISC?
- Hardware is simpler to build with fewer circuits needed for carrying out complex instructions
- Each instruction takes the same amount of time, one clock cycle, allows for pipelining to be possible
- Ram is cheap, RISC’s use of RAM and software allows better performance processors at a lower cost.
How do multi core processors achieve higher performance?
They distribute workload across multiple processor cores, achieving significantly higher performance by performing several tasks in parallel ( also known as parallel systems.
What is a disadvantage of multi core processing?
• Speed increase is dependent on the software being able to utilise parallel processing capabilities, some applications may not use all the cores.
What is a co processor?
An extra processor used to supplement the functions of the primary processor ( CPU ).
What can the co processor be used for?
• Perform floating point arithmetic, graphics processing, digital signal processing.
What is a disadvantage of co processors?
- Only carries out a limited range of functions
- Can not be a normal processor, as it for example does not have the ability to fetch its own instructions, do input and output operations
What is a GPU?
A graphics processing unit is a specialised electronic circuit which is very efficient at manipulating computer graphics and image processing.
